下载文档原格式
小学下册英语第2单元期中试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1._____ (weeds) can compete with other plants.2.The Andromeda Galaxy is the closest galaxy to the ______.3. A fault line is a location where tectonic plates ______.4.I have a _____ (玩具枪) for dress-up.5.The _______ (The Panama Canal) connects the Atlantic and Pacific Oceans.6.The ______ (生态恢复) involves planting native species.7.My favorite part of the day is ______.8.What do you call a large body of saltwater?A. LakeB. OceanC. RiverD. Pond9. A __________ can often be found building dams in rivers.10.What is the shape of a stop sign?A. CircleB. TriangleC. OctagonD. SquareC11.I have ______ in my backpack.12.He can _____ a bicycle. (ride)13.The birds are ______ in the trees. (chirping)14.We can _______ a fun project together.15.My ________ (玩具名称) is a special gift from my parents.16.What do we call the process by which trees lose their leaves?A. PhotosynthesisB. GerminationC. DeciduousnessD. DormancyC17.We play hide and ______ (找) in the garden.18. A ______ (植物保护) initiative can help endangered species.19.The cat is _____ (small/big).20.The _____ (star/planet) is bright.21.The chemical formula for sodium bicarbonate is _______.22.We can see the _____ (moon/stars) at night.23.What do you call the young of a llama?A. CriaB. CalfC. KitD. PupA24.The main component of natural gas is _______.25.I want to ___ a superhero. (become)26.What is the main ingredient in hummus?A. ChickpeasB. LentilsC. BeansD. Peas27.The chemical formula for acetic acid is __________.28.What is the largest organ in the human body?A. BrainB. SkinC. HeartD. LiverB29.The chemical symbol for nitrogen is _____.30.What do we call the chemical process that occurs in living organisms to produce energy?A. Cellular respirationB. PhotosynthesisC. FermentationD. MetabolismA Cellular respiration31.What is the primary purpose of a map?A. To tell timeB. To guide travelersC. To measure distancesD. To show weatherB To guide travelers32.They play _____ (football) after school.33.What is the main ingredient in bread?A. RiceB. FlourC. SugarD. Salt34.My favorite snack during movies is _______ (爆米花).35.What do we call a shape with four equal sides?A. RectangleB. SquareC. TriangleD. CircleB36.What do we use to brush our teeth?A. CombB. ToothbrushC. TowelD. SpoonB Toothbrush37.How many players are on a soccer team?A. 10B. 11C. 12D. 1338. A ________ (植物特性研究) reveals adaptations.39.Which of these is a winter sport?A. SwimmingB. SkiingC. SurfingD. RunningB40.The ______ helps with the immune system.41._____ (植物演化) shows how species adapt over time.42.I want to _______ (学习) about different cultures.43.My brother often plays _______ (名词) with his friends. 他觉得这个游戏很_______ (形容词).44.The ancient Romans built roads that connected __________ (城市).45.We play _____ (games) on weekends.46.What is the name of the famous volcano in Italy?A. Mount EtnaB. Mount VesuviusC. Mount StromboliD. Mount Olympus47. A __________ (化学生态) studies interactions between chemicals and living organisms.48.The chemical symbol for manganese is ____.49. A ferret is often kept as a _______ (宠物).50.My aunt is married to my __________. (叔叔)51.My grandmother is my favorite _______ because she tells stories.52.I wear a ___ (hat/scarf) in winter.53.What do you call a person who studies ancient civilizations?A. ArchaeologistB. HistorianC. AnthropologistD. SociologistA54.What is the name of the famous scientist who developed the theory of relativity?A. Isaac NewtonB. Albert EinsteinC. Nikola TeslaD. Galileo GalileiB55.I can ______ (表达) my thoughts in writing.56.This is my favorite . (这是我最喜欢的。
2022年考研考博-考博英语-浙江大学考试全真模拟易错、难点剖析AB卷（带答案）一.综合题(共15题)1.单选题It is astonishing to know that children and youth ( ) the biggest segment of the country's homeless population.问题1选项A.substitute forB.make outC.make upD.make up for【答案】C【解析】substitute for代替，取代；make out理解，认出；make up有很多意思，这里指组成；make up for弥补，补偿。
句意：令人惊讶的是，儿童和青年构成了该国无家可归人口的最大部分。
选项C符合句意。
2.单选题A theory is an organized set of principles that is designed to explain and predict some phenomenon. Good theories also provide specific testable predictions, or ( ) about the relation between two or more variables.问题1选项A.hypothesisB.conceptionC.ideaD.meaning【答案】A【解析】hypothesis假设；conception概念，设想；idea想法，主意；meaning意义，意图。
句意：理论是一套有组织的原理，用来解释和预测一些现象。
好的理论也提供了具体的可测试的预测，或者关于两个或两个以上变量之间关系的假设。
选项A符合句意。
3.单选题It is disturbing to note how many crimes we do know about were detected（） , not by systematic inspections or other security procedures.问题1选项A.by accidentB.on scheduleC.in generalD.at intervals【答案】A【解析】by accident偶然，意外的；on schedule按时；in general总之，通常；at intervals不时。
小学上册英语第6单元暑期作业(有答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The goldfinch's song is pleasant to ______ (听).2. A frog's legs help it swim and ______ (跳).3.I love playing with my ________ (玩具车) on the floor.4.My cousin is always . (我的表兄弟/表姐妹总是。
)5.The process of separating components of a mixture using a filter is called _______.6.The ____ has sharp claws and is very agile.7.He likes to play _______.8.What do you call a young female chimpanzee?A. InfantB. PupC. CubD. Kit答案: A9.The ice cream truck is ______ (coming) down the street.10.The wind blows through the ______ (树叶). It sounds very ______ (宁静).11. A supernova is the explosion of a dying ______.12.ts can grow from __________ (切割). Some pla13.The chemical formula for citric acid is ________.14.The _______ has a variety of colors and shapes.15.I can ______ (识别) different species of birds.16.Chemical energy is stored in the bonds of ______.17.We can _______ (一起) read a book.18.The butterfly starts as a _________ (毛毛虫).19.Mahatma Gandhi led India to independence through ______ (非暴力) resistance.20.The _______ of an object can be affected by the surface it is on.21.The basic building blocks of matter are called _____.22.The ________ (季节性) affects flowering times.23.The ________ is green and leafy.24.I like to customize my ________ (玩具) with stickers.25.The sun rises in the ______ (east).26.__________ (有机化合物) contain carbon and are found in living things.27.The __________ is a famous area known for its artistic contributions.28.My dad enjoys going to the ____ (movies).29.What is the name of the famous river in China?A. YangtzeB. MekongC. GangesD. Indus答案:A30.The ______ is the largest bird that cannot fly.31.The ______ is a symbol of peace.32.The ______ (小鹿) grazes in the open field, enjoying the warm ______ (阳光).33. A _____ can be very bright and is often seen at night.34.The process of using heat to break down a substance is called _______.35.My ________ (玩具名称) inspires me every day.36. A neutral solution has equal concentrations of ______.37.The capital of the Netherlands is _______.38.What is the term for the outer layer of the atmosphere?A. TroposphereB. StratosphereC. MesosphereD. Exosphere答案:D.Exosphere39.I enjoy learning about history, especially __________.40.What do you call the scientific study of the mind and behavior?A. PsychologyB. SociologyC. AnthropologyD. Psychiatry答案: A41.I always help my mom with ______.42.The _____ (trophy) is shiny.43.She likes to play with her ___. (friends)44.They are eating ________ for lunch.45.The _____ (spaceship) Apollo 11 took astronauts to the moon.46.The main source of energy for the Earth is _____.47.She is wearing a cute ___. (outfit)48.Mice are known for being very _________ (敏捷).49.The process of freezing turns a liquid into a __________.50.The symbol for carbon is _______.51.The cat is ________ on the sofa.52.The chemical formula for propane is ______.53.I have a new ___. (computer)54.The ________ was a vital treaty that shaped international relations.55.The _____ (植物保护) is important for biodiversity.56. Wall of China was built to protect against ________. The Grea57.What do we call a person who studies the nature of reality?A. PhilosopherB. ScientistC. MathematicianD. Historian答案: A58. A ____ is a curious animal that explores new places.59.I love to watch the stars at ______ (夜晚). They twinkle like ______ (宝石).60.She is _______ (coloring) a picture.61.What is the name of the famous landmark in Paris?A. Eiffel TowerB. Louvre MuseumC. Arc de TriompheD. All of the above答案: D. All of the above62.What is the name of the famous landmark in Paris?A. Eiffel TowerB. Big BenC. Statue of LibertyD. Colosseum答案:A63.The _______ can provide essential food for animals.64.The ____ is a small rodent that likes to nibble on seeds.65.The chemical symbol for potassium is _______.66.The _______ (猫头鹰) hoots at night.67.The _______ (The Industrial Revolution) revolutionized manufacturing processes.68.My brother is a __________ (创新型人才).69.What do you call the person who writes books?A. AuthorB. EditorC. PublisherD. Journalist答案:A70.The process of changing a liquid to a gas is called __________.71.My cousin is a very good ____ (swimmer).72.The _____ (carnivorous) plants trap insects for nutrients.73.My favorite place is the ______ (海边).74.The garden is _______ (色彩斑斓的).75.The capital of Turkey is _____.76.Which animal is known for its long neck?A. GiraffeB. ElephantC. RhinoD. Hippo答案: A77.The ______ helps us learn about community service.78.My brother is interested in ____.79.The ____ is often seen fluttering around in the garden.80.The ______ (青蛙) can be found in many environments.81.What is the name of the famous British scientist known for his work on gravity?A. Albert EinsteinB. Isaac NewtonC. Charles DarwinD. Stephen Hawking答案:B82. A _______ (蟋蟀) chirps at night.83.______ is the process of breaking down rocks into smaller pieces.84. A ________ (蝴蝶) flutters around and is very colorful.85.The _____ (wind/snow) is blowing.86.The Earth’s surface is constantly changing due to ______ and erosion.87.They are ___ a picture. (taking)88.My pet is a small ____.89.The Earth's layers include the crust, mantle, outer core, and ______ core.90.The parade was ________ (精彩).91.The __________ (历史的激励作用) drive progress.92.I enjoy _____ (tasting) different herbs.93.The __________ (历史的践行) embodies principles.94.What is the name of the famous American author known for "To Kill a Mockingbird"?A. Harper LeeB. F. Scott FitzgeraldC. Ernest HemingwayD. Mark Twain答案: A. Harper Lee95.My cat's _______ (反应) is very quick.96.The iguana changes its ______ (颜色) to blend in.97.The chemical formula for table salt is _______.98. A ________ (树木) is essential for clean air.99.What is the name of the famous landmark in Paris?A. Eiffel TowerB. Big BenC. Statue of LibertyD. Colosseum答案: A100.My friend is a _____ (志愿者) who helps others.。
2024年10版小学5年级上册英语能力测评(含答案)考试时间：80分钟（总分:120）A卷一、综合题(共计100题共100分)1. 选择题：What do we call the time when it is very hot?A. WinterB. SpringC. SummerD. Autumn2. 填空题：A kitten loves to play with a _______ string.3. 听力题：The Earth's crust is made up of tectonic ______.4. 听力题：The pH scale ranges from to ______.5. 填空题：We visit the ______ (农场) to learn about agriculture.6. 听力题：A solution that contains dissolved salts is called a _______ solution.7. 选择题：What do we use to cut paper?A. RulerB. ScissorsC. GlueD. Tape答案: B8. 选择题：Which one of these is a primary color?A. GreenB. BlueC. PurpleD. Orange9. 选择题：What do we call a collection of books?A. LibraryB. BibliographyC. AnthologyD. Archive答案: A. Library10. 听力题：A ______ is a large body of gas that emits light.11. 听力题：Many _______ require specific light conditions.12. 听力题：__________ are used to improve the flavor of food.13. 选择题：What is the name of the famous landmark located in Washington D.C.?A. Statue of LibertyB. Golden Gate BridgeC. Lincoln MemorialD. Mount Rushmore答案：C14. 填空题：The capital of Burundi is ________ (吉特根).15. 听力题：We will go ______ to see the fireworks. (outside)16. 填空题：The spider spins a ______ (网) to catch flies.17. 选择题：What is the name of the first man on the moon?a. Yuri Gagarinb. Neil Armstrongc. Buzz Aldrind. John Glenn答案:B18. 听力题：I have ___ (two/three) pets at home.19. 选择题：What is the main ingredient in pizza?A. BreadB. CheeseC. Tomato sauceD. All of the above答案: D20. 听力题：Australia is known for its unique __________.21. 听力题：The vegetables are _____ (fresh/old) at the market.22. 听力题：Star formation occurs in regions of space called molecular _______.23. 听力题：I _____ (love/hate) homework.24. 选择题：What do you call a young parrot?A. ChickB. KitC. PupD. Fawn答案:A25. 听力题：My mom cooks ________ dinner.26. 听力题：The dog is _______ (running) after the ball.27. 选择题：What is the name of the famous artist known for his "The Girl with a Pearl Earring"?A. Johannes VermeerB. RembrandtC. Vincent van GoghD. Claude Monet答案: A28. 听力题：The capital of Kazakhstan is __________.29. 听力题：I have a ___ (sister/brother) and a dog.30. 填空题：The _____ (叶子) of the tree turn yellow in autumn.31. 选择题：What do you call the place where we watch movies?A. LibraryB. CinemaC. ParkD. School32. 听力题：The Titanic sank on its maiden ________.33. 填空题:My favorite fruit is ________ because it is sweet.34. 听力题：A _______ reaction occurs when energy is absorbed.35. 听力题：The _____ (kite/balloon) is flying high.36. 听力题：The process of fermentation can produce __________ and carbon dioxide.37. 听力题：I like to ______ my friends after school. (meet)38. 填空题：I saw a _______ (小松鼠) gathering acorns.39. 选择题：Which season comes after winter?A. FallB. SpringC. SummerD. Monsoon40. 听力题：The chemical formula for methanol is ______.41. 选择题：Which instrument has keys and is played with fingers?A. ViolinB. GuitarC. PianoD. Drums42. 选择题：What is the name of the famous American author known for "Little Women"?A. Louisa May AlcottB. Mark TwainC. F. Scott FitzgeraldD. Ernest Hemingway答案: A. Louisa May Alcott43. 填空题：I like to collect _________ (模型) cars because they are _________ (精致的).44. 听力题：A solution that does not conduct electricity is called a _______.45. 听力题：A __________ is a flat area of land that is higher than the surrounding land.46. 填空题：A dolphin jumps gracefully out of the _______ and plays.47. 填空题：A _____ (鱼) swims happily in the water. It has shiny scales. 一条鱼在水中快乐地游泳。
南昌2024年07版小学六年级英语第五单元暑期作业(含答案)考试时间：80分钟（总分:140）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、What do we call the study of living organisms?A. BiologyB. ChemistryC. PhysicsD. Geology答案: A2、填空题：I love to read ________ (书) before going to bed.3、填空题：The __________ (历史的回忆) enriches our understanding.4、What do you call a place where you can borrow books?A. StoreB. LibraryC. SchoolD. Park答案:B5、听力题：The main component of the Earth’s crust is _______.6、听力题：The ______ helps us understand the world.7、biodiversity hotspot) is rich in various species. 填空题：The ____8、What is the name of the popular animated series about a family of superheroes?A. The IncrediblesB. The SimpsonsC. Family GuyD. Avatar答案: A9、填空题：I want to learn how to _______ (技能). It could help me in my future _______ (职业).10、River is the longest ________ (河流) in Africa. 填空题：The Norm11、What do you call the first meal of the day?A. LunchB. DinnerC. BreakfastD. Snack答案:C12、听力题：A process that separates a mixture into its components is called ______.13、听力题：We are going to a ______ (concert) next month.14、What is the main focus of a compass?A. NorthB. SouthC. EastD. West答案:A15、What is the name of the famous painting by Leonardo da Vinci?A. The Starry NightB. The Last SupperC. Mona LisaD. The Scream答案: C16、听力题：The ____ has soft, fuzzy fur and loves to cuddle.17、听力题：The dog is _____ at the ball. (looking)18、听力题：She likes to eat ___ for breakfast. (pancakes)19、听力题：We see ___ (clouds/stars) in the sky.20、填空题：My favorite toy is a ________ that I can draw.21、填空题：The ________ was a landmark event in the history of education reform.22、How do you say "book" in Spanish?A. LibroB. LibriC. BookeD. Libros23、听力题：The Earth's layers have different ______ characteristics.24、填空题：The __________ (古代希腊的城邦) were independent city-states.25、听力填空题：During school breaks, I usually __________ with my family.26、听力题：Christopher Columbus sailed across the ocean in ________.27、填空题：The _______ (Socrates) is considered one of the founders of Western philosophy.28、听力题：The chemical symbol for rubidium is ______.29、填空题：The _____ (环境) can influence how plants grow.30、填空题：The ________ is a lovely plant that grows quickly.31、听力题：I can ________ (imagine) a better world.32、What is the name of the sweet treat made from cocoa?A. CandyB. Ice CreamC. ChocolateD. Cake答案: C33、听力题：The playground is ___ (fun) to play in.34、填空题：The _____ (猫) is known for its independence.35、填空题：The monkey swings from ________________ (树).36、填空题：I like to play _____ (棋类游戏) with my friends.37、填空题：A frog's skin can absorb ______ (水).38、填空题：The _______ (老虎) is known for its stealth.39、听力题：She is wearing a warm ___. (sweater)40、What is the capital of Ethiopia?A. Addis AbabaB. NairobiC. KampalaD. Khartoum答案: A. Addis Ababa41、填空题：The __________ is a large body of ice moving slowly down a mountain. (冰川)42、What do we call a baby frog?A. TadpoleB. KittenC. PuppyD. Chick答案:A43、听力题：The process of ______ occurs when rocks are subjected to extreme heat.44、What do you call a place where you can see wild animals?A. ZooB. SafariC. National ParkD. Wildlife Reserve答案:A45、听力题：The Sun is classified as a yellow ______ dwarf.46、填空题：My pet ___ (鸟) sings beautiful songs.47、What do we call the period before a baby is born?A. PregnancyB. ChildhoodC. AdolescenceD. Adulthood48、What is the name of the famous American singer known for "Like a Prayer"?A. MadonnaB. Lady GagaC. Britney SpearsD. Janet Jackson答案：A49、听力题：My dad is very ________.50、听力题：I love to ________ with my friends.51、听力题：A _______ is a type of force that pulls objects toward the Earth.52、听力题：A __________ can often be seen perched on a branch.53、填空题：The ancient Egyptians believed in _______ to guide them in the afterlife. (神灵)54、填空题：The _____ (植物细胞) are unique to plants.55、听力题：Dark matter makes up a large part of the universe but cannot be ______ directly.56、听力题：The capital city of Hungary is __________.57、填空题：My favorite place to visit is the ________ (博物馆).58、填空题：My _____ (叔叔) is a doctor.59、填空题：My uncle loves to __________ (钓鱼) on weekends.60、填空题：They are playing _______ (足球) in the yard.61、听力题：Chemical symbols represent ________ in a chemical equation.62、What is the capital of Tuvalu?a. Funafutib. Nukufetauc. Niutaod. Vaitupu答案:a63、听力题：The Great Barrier Reef is located off the coast of _______.64、填空题：The park is _______ (适合家庭).65、听力题：Metals are usually ________ conductors of electricity.66、填空题：We should _______ (保持) a positive attitude.67、填空题：My sister, ______ (我姐姐), enjoys sewing and crafting.68、What is the capital of Portugal?A. LisbonB. PortoC. Faro答案:A69、填空题：The __________ was a major event in US history that abolished slavery.70、听力题：A __________ is a reaction that involves oxidation and reduction.71、听力题：My mom enjoys writing ____ (letters).72、选择题：What do we call a person who runs a business?A. EmployeeB. EmployerC. ManagerD. Boss73、听力题：Ice is the _____ form of water.74、What is the name of the ancient city buried by volcanic ash?A. AthensB. PompeiiC. RomeD. Carthage75、听力题：She has a pet ______. (fish)76、填空题：I love _______ (玩) with my pets.77、What do you call an animal that is active at night?A. DiurnalB. NocturnalC. CrepuscularD. Seasonal答案:B78、填空题：The ______ (青蛙) is often found near water.79、Which day comes after Monday?A. SundayC. WednesdayD. Thursday80、听力题：A balanced chemical equation has the same number of atoms on both _____.81、填空题：The squirrel's diet consists mainly of ________________ (坚果) and seeds.82、Which of these is a flying insect?A. AntB. BeetleC. ButterflyD. Worm答案:C83、填空题：中国的________ (art) 在历史上有着丰富的表现形式。
![小学上册第2次英语第三单元综合卷[有答案]](https://img.taocdn.com/s1/m/f8da5f5211661ed9ad51f01dc281e53a59025109.png)
小学上册英语第三单元综合卷[有答案]英语试题一、综合题(本题有50小题，每小题1分，共100分.每小题不选、错误，均不给分)1 The _______ of an object can change based on its position.2 What do we call a scientist who studies animal behavior?A. EthologistB. ZoologistC. BiologistD. Ecologist答案: A3 A non-metal usually gains ______ in a reaction.4 What do you call the people living in a city?A. CitizensB. ResidentsC. LocalsD. All of the above答案:D5 The butterfly flutters around the ____.6 A substance that speeds up a chemical reaction is called a ______.7 How many bones are in the adult human body?A. 206B. 208C. 210D. 212答案:A8 What is the main ingredient in salad dressing?A. OilB. WaterC. SugarD. Salt答案:A9 My dad likes to go cycling in the ____ (park).10 My favorite singer is _______ (某个歌手).11 We will visit our ______ (grandparents) next week.12 The bear searches for food in the ____.13 The stars are ___. (shining)14 The ______ (木本植物) includes trees and shrubs.15 The goat has curved ______ (角).16 A cave is formed by the erosion of ______ by water over time.17 What do you call the person who cooks food?A. BakerB. ChefC. WaiterD. Server答案:B18 The chemical symbol for manganese is ________.19 My mom is my __________ (榜样) because she works very hard.20 The _____ (狮子) protects its territory fiercely.21 I tell my __________ about my day. (妈妈)22 My favorite form of exercise is _______ (游泳).23 We enjoy _____ (exploring) new places.24 What is the name of the famous bear in "Winnie the Pooh"?A. PaddingtonB. BalooC. WinnieD. Yogi答案: C25 _____ (thyme) is used in many dishes.26 I can ______ (制定) plans for the future.27 In which month do we celebrate Christmas?What is the capital of France?A. LondonB. ParisC. Rome28 I enjoy ______ in the sunshine. (playing)29 What is the name of the famous statue in Rio de Janeiro?A. Christ the RedeemerB. Liberty Enlightening the WorldC. DavidD. Venus de Milo30 My father is a . (我爸爸是个。
小学下册英语第1单元期末试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The ________ was a leading figure in the quest for racial equality.2.What do you wear on your head?A. ShoesB. HatC. GlovesD. Scarf3.The chemical formula for potassium hydrogen phthalate is _____.4.The capital of Kuwait is _______.5.The chemical formula for sodium nitrite is ______.6.What is the freezing point of water?A. 0°CB. 100°CC. 50°CD. 25°C答案:A7.My aunt is a ______. She loves to volunteer.8.The ______ helps protect the environment.9.What is the capital of Cyprus?A. NicosiaB. LimassolC. LarnacaD. Famagusta10.Which country is known for the kangaroo?A. CanadaB. AustraliaC. ChinaD. Brazil答案:B11.The picture is on the ___. (wall)12.The capital of Qatar is _______.13.My favorite musician is _______.14.The _____ (fish/bird) is swimming.15.What do we call the time of day when the sun rises?A. NoonB. MorningC. EveningD. Midnight答案:B16.The skunk's spray is a powerful ________________ (防御).17.The pH scale measures how ______ or basic a solution is.18. A ______ (狮子) lives in prides with its family.19.What do you call the art of folding paper into shapes?A. SculptureB. OrigamiC. DrawingD. Painting答案:B20.The _______ (鲸鱼) communicates with others through songs.21.How many fingers do humans typically have?A. 8B. 10C. 12D. 1422.My mom cooks __________ for dinner. (美味的食物)23.The capital of Botswana is __________.24.I need a ________ (friend) to talk to.25.The engineer, ______ (工程师), invents new gadgets.26.What do you need to write on a board?A. PenB. MarkerC. PencilD. Paint27.The study of Earth's geology helps us understand ______ processes.28.I got a new _____ (飞机) for my birthday.29. A __________ is a type of reaction that produces gas bubbles.30.The rain is ___. (pouring)31.How many colors are in the American flag?A. 2B. 3C. 4D. 5答案:B32.The first President of the United States was elected in _______.33.I always try to help my classmates when they need ________ (帮助) with their work.34.The capital of Iceland is ________ (雷克雅未克).35. A __________ is a natural feature that can be seen from afar.36.How long is a day on Mercury?A. 24 hoursB. 59 Earth daysC. 88 Earth daysD. 56 Earth days37.Many animals rely on __________ for their survival.38.What is the tallest mountain in the world?A. KilimanjaroB. K2C. EverestD. Alps答案:C39. A _____ can be millions of light-years away from Earth.40.What is the capital of Italy?A. VeniceB. MilanC. FlorenceD. Rome答案:D41.My _______ (狗) loves to play fetch with a stick.42.Which planet is closest to the sun?A. EarthB. VenusC. MercuryD. Mars43. A _______ is a high, steep face of rock.44.What is 3 + 5?A. 5B. 6C. 7D. 845.What is 3 x 3?A. 6B. 7C. 8D. 9答案:D46.The first African American to serve as President was _______. (奥巴马)47.She is a great ________.48.The first modern Olympic Games were held in ________ (1896).49.The chemical formula for hydrogen peroxide is ______.50.The store opens _____ (early/late) in the morning.51.What is the value of 7 × 6?A. 42B. 48C. 54D. 60答案:A52.The chemical formula for ammonium acetate is __________.53.My collection of ________ (玩具名) is getting bigger! I hope to have a ________ (形容词) display for them soon.54.The _____ (狐狸) is very sly.55.The ________ has a unique pattern on its skin.56. A _____ (盆栽) can brighten up a room.57. A _______ is a solid that forms during a chemical reaction in solution.58.The book is ________ the shelf.59.What do we call a baby deer?A. FawnB. CalfC. KidD. Lamb答案:A60.What is 10 - 4?A. 2B. 5C. 6D. 761.of Hammurabi is one of the oldest known ______ (法律). The Cold62.He is a _____ (工程师) who builds bridges.63.I have a ________ that brightens my day.64.The ______ (小鼠) scurries quickly around the house.65.What do you call a young hyena?A. CubB. KitC. PupD. Fawn答案:A66.I like _____ (吃) pizza.67. A __________ is formed by the interaction of geologic processes and human activity.68.Which animal is known for its ability to change colors?A. ChameleonB. ParrotC. FlamingoD. Penguin69.The _____ can vary in brightness and color.70.What do you call a baby pig?A. PigletB. CalfC. KidD. Foal答案:A71.The _____ (生态研究) helps protect endangered plants.72.The puppy is ______ at the ball. (playing)73.What is the term for a person who studies dinosaurs?A. PaleontologistB. ArchaeologistC. GeologistD. Biologist答案:A74.There are ten _____ (students) in the class.75.What is 15 divided by 3?A. 3B. 4C. 5D. 6答案:C76.The ________ (农业生态学) is essential for sustainability.77.I have a collection of ______ (邮票) from many different countries.78.Which animal says "quack"?A. DogB. CowC. DuckD. Sheep答案:C79.Where do fish live?A. TreesB. WaterC. SkyD. Ground80.Coal is a type of ______ rock that is formed from ancient plants.81.The ______ (小鸟) builds its nest high in the tree.82.The _____ (海豹) basks on the rocks in the sun.83. A __________ is a substance that speeds up a chemical reaction.84.Listen and number.听录音，给下面的图片标出正确的顺序。
小学上册英语第一单元测验试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The boiling point of a substance is the temperature at which it turns to _______.2.In the zoo, we saw a _______ (大象) spraying water with its trunk.3.He is a _____ (评论员) offering insights into current events.4.What is the capital of Ethiopia?A. Addis AbabaB. NairobiC. AsmaraD. DjiboutiA5.The puppy is very ________.6.Which part of your body helps you to see?A. EarsB. EyesC. NoseD. MouthB7.The ________ (博物馆) showcases local history.8.What is the main function of the heart?A. To digest foodB. To pump bloodC. To filter wasteD. To breatheB To pump blood9.Vinegar is an example of an ______ solution.10.ts can ______ (通过分枝) to spread. Some pla11.It is _____ outside today. (cold)12.What do we call the famous wall in China?A. Great WallB. Berlin WallC. Hadrian's WallD. Wall of JerichoA13.What do we call a person who travels to space?A. AstronautB. PilotC. ScientistD. EngineerA14.The rabbit is ________ carrots.15.What do we call a baby rabbit?A. KittenB. BunnyC. PupD. Calf16.The Aztecs were known for their _______ civilization.17.The ancient Greeks engaged in ________ to settle disputes.18.of Mexico is located ________ (在美国南部). The Gupt19.What is the main purpose of a map?A. To show roadsB. To provide directionsC. To represent areasD. All of the above20.What do you call a group of wolves?A. PackB. FlockC. GaggleD. MurderA21.I love to sing ______ songs.22.I like to draw ______ (漫画人物) and create my own ______ (故事).23.I made a scrapbook of my favorite ________ (回忆) from summer camp. It’s full of ________ (照片).24.Space is a vacuum, meaning it has very little _______.25. A cat's agility helps it catch ______ (猎物).26.The _______ of a wave can be determined by its wavelength.27.Which of these is an ocean?A. AmazonB. NileC. AtlanticD. Mississippi28.The __________ can be quite chilly during autumn. (天气)29.What is the soft drink made from cola?A. TeaB. CoffeeC. ColaD. Juice30.我的朋友喜欢 _______ (活动). 她觉得这很 _______ (形容词)31.Sarah is a ______. She enjoys writing poems.32.What is the term for a person who travels to different countries?A. TouristB. ExplorerC. TravelerD. AdventurerA33. A ______ is a geological feature that attracts scientists and researchers.34. A _______ is a type of reaction that breaks down compounds into simpler substances.35.My ________ (玩具名称) is a fun friend.36.The ________ (根茎植物) can be edible.37. A __________ is a geological feature formed by the action of waves on rock.38.What is the name of the famous ship that sank in 1912?A. Queen MaryB. TitanicC. BritannicD. LusitaniaB39.What is the name of the fairy tale character who lost her glass slipper?A. Snow WhiteB. CinderellaC. ArielD. BelleB40.The city of Dublin is the capital of _______.41. A garden can provide a ______ (美丽的) view in your backyard.42.What do you call a large, round fruit that is typically orange?A. AppleB. PeachC. OrangeD. Banana43.The chemical formula for glucose is _____ (CHO).44.The __________ in summer is often very hot and dry. (天气)45.Plants need _______ to grow.46.The chemical symbol for molybdenum is _____.47.What is the name of the largest land animal?A. RhinoB. ElephantC. HippoD. GiraffeB48.In 1492, Columbus sailed the ocean blue to find a new __________. (航道)49.What is the capital city of Moldova?A. ChișinăuB. BălțiC. TiraspolD. Bender50.The jackal is a clever ______ (动物).51.What do you call a person who plays chess?A. PlayerB. Chess masterC. StrategistD. Chess player52.What do we call the part of the plant that produces seeds?A. FlowerB. LeafC. StemD. RootA53.The ice cream is ___. (cold)54.My friend is a ______. He enjoys hiking.55.What is the name of the famous ship that sank on its maiden voyage?A. TitanicB. LusitaniaC. BritannicD. Andrea DoriaA56.I have a red ______ (气球) for my birthday party. It floats high in the ______ (天空).57.I see a _____ (rainbow) in the sky.58. A chemical reaction can be classified based on the ______.59. A process that separates a substance from a mixture is called ______.60.How many wheels does a bicycle have?A. 2B. 4C. 3D. 161.The capital city of Saint Kitts and Nevis is __________.62.I sometimes make up stories about my ________ (玩具名). They have their own ________ (名词) and adventures.63.My mom enjoys __________ (旅行) to new places.64.What do we call the person who repairs shoes?A. TailorB. CobblerC. BakerD. Mechanic65.My sister is my best _______ who is always ready to help.66.The parrot has a bright ______ (羽毛).67.I enjoy participating in ______ (学校项目) that focus on community service. It’s rewarding to give back.68.For breakfast, I usually eat ______ (面包) and drink ______ (牛奶). It gives me energy for the day.69.Mount Everest is located in the __________ mountains.70.The _______ (小蜗牛) carries its house on its back.71.My favorite animal is a ______ (猴子) because they are funny.72.Did you see a _______ (小老鼠) in your house?73. A _______ can be a fun project for children.74.What is the color of a typical sunflower?A. YellowB. GreenC. BlueD. RedA75.The dolphin makes clicking ______ (声音).76.They play _____ (hide-and-seek).77.Which color is a ripe strawberry?A. BlueB. GreenC. RedD. YellowC Red78.We will _______ (celebrate) my birthday tomorrow.79.What is the capital city of Bangladesh?A. DhakaB. ChittagongC. KhulnaD. Sylhet80.The lizard basks in the _________. (阳光)81.What do we call the study of ancient civilizations?A. ArchaeologyB. AnthropologyC. SociologyD. HistoryA82.The __________ is a major geographical region in Africa. (撒哈拉沙漠)83.Many _______ need sunlight to grow.84.The ________ (气候适应) is essential.85.The __________ (历史的启迪) guides our path.86.The chemical symbol for rhenium is ____.87.What is the term for a baby goat?A. CalfB. KidC. FoalD. LambB88.The man has a funny ________.89.The dog is _______ (wagging) its tail.90.The garden is ________ (五颜六色).91.The __________ is a region known for its deserts and dry climate.92.I like to listen to ________ (古典音乐) while studying.93.My favorite activity in the spring is ______ (种花).94.Which of these is a vegetable?A. AppleB. CarrotC. BananaD. Grape95. A mixture of solids is called a ______ blend.96.What is 20 7?A. 12B. 13C. 14D. 1597.We like to go to the ___ (beach/mountains).98.The __________ (历史研究) helps us understand the past.99.The main component of the Earth's atmosphere is __________. 100.The __________ (历史的纪录片) provide visual representations.。
小学上册英语第四单元自测题[含答案]英语试题一、综合题(本题有50小题，每小题1分，共100分.每小题不选、错误，均不给分)1 What do we call a snowman’s nose?A. StickB. CarrotC. RockD. Button答案:B2 Which animal is known for its long neck?A. ElephantB. GiraffeC. ZebraD. Rhino答案: B3 The ______ is a successful businessperson.4 My favorite holiday is ______.5 A __________ (分子结构分析) reveals information about compound properties.6 Ants can carry items many times their ______ (重量).7 What do you call a story that is not real?A. FactB. FictionC. BiographyD. History8 The Earth's interior contains both solid and ______ components.9 What is the main ingredient in bread?A. FlourB. SugarC. SaltD. Water10 The __________ (历史的启示) guides our actions.11 The capital of the United Arab Emirates is ________ (阿联酋的首都是________).12 We can paint a ________ together.13 My uncle teaches me how to ____.14 My brother is a ______. He enjoys playing sports.15 The clock ticks _____ (slowly/quickly).16 The __________ is a famous tourist destination in Asia.17 The man has a funny ________.18 A chemical reaction may produce gas, solids, or _____.19 A chemical reaction can indicate a change in ______.20 How many continents are there in the world?A. 5B. 6C. 7D. 821 The invention of the light bulb changed the way people _____.22 The ______ is a talented gardener.23 My favorite part of the day is ______.24 The ______ teaches us about world cultures.25 The _____ (海狮) barks loudly.26 The cat curls up on a _____ soft blanket.27 What do you call the person who teaches students?A. DoctorB. TeacherC. EngineerD. Chef答案:B28 Where do most bees live?A. TreeB. HiveC. WaterD. Ground29 A tarantula can defend itself with its ______ (毒螯).30 What is the name of the large desert in Africa?A. SaharaB. GobiC. KalahariD. Atacama31 The flowers are ___ (blooming) in the garden.32 What is the opposite of 'big'?A. SmallC. HugeD. Tall33 The ant is very _________. (勤劳)34 We saw a ______ at the pet store.35 What is 3 + 5?A. 6B. 7C. 8D. 936 The cheetah's acceleration is unmatched in the animal ________________ (王国).37 What do you call a group of fish?A. SchoolB. PackC. FlockD. Herd答案: A38 My friend is a ______. He enjoys collecting coins.39 They are ___ (singing/playing) together.40 What is the main ingredient in a burrito?A. RiceB. TortillaC. MeatD. Beans41 What is the name of the famous Italian dish made with pasta and tomato sauce?B. PizzaC. SpaghettiD. Risotto42 The leaves change _______ in the fall, making the world beautiful.43 The process of ______ can create sedimentary layers in rocks.44 My mom loves __________ (参与公益活动).45 I like to play ______ with my siblings.46 Read and choose.(看图选择。
海口“PEP”24年小学四年级上册英语第二单元暑期作业考试时间：90分钟（总分:110）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、填空题：The _____ (根茎) stores nutrients for the plant.2、What is the main reason we see different phases of the moon?A. Distance from EarthB. Sunlight reflectionC. Earth's shadowD. Rotation speed3、What is the capital of Australia?a. Sydneyb. Melbournec. Canberrad. Brisbane答案:c4、听力题：The dog is ______ (barking) at the strangers.5、What do you call a baby turtle?A. HatchlingB. PupC. CalfD. Kit答案:A6、填空题：The _____ (种子) can remain dormant for years.7、听力题：The dog wags its ______ (tail) when excited.8、What do you call a place where you can see animals?A. AquariumB. ZooC. CircusD. Park答案:B9、填空题：The __________ (历史的力量) can unite or divide.10、填空题：A turtle moves ______ (慢) but can live a long time.11、听力题：The ocean is very ________.12、听力题：A _____ is a star that has used up its nuclear fuel.13、填空题：The ancient Greeks believed in many _____ and myths.14、What is the capital of Somalia?a. Mogadishub. Hargeisac. Kismayod. Baidoa答案:a15、填空题：He is a _____ (营销专家) who promotes products.16、填空题：The _______ (The Cuban Revolution) led to a communist government in Cuba.17、填空题：I like to watch ______ (电影) that inspire me.18、听力题：I love to ___ (cook/eat) with friends.19、填空题：Certain plants are known for their ability to attract ______ and beneficial insects. (某些植物以其能吸引授粉者和有益昆虫而闻名。
a rXiv:as tr o-ph/64247v111Apr26The B-Supergiant Components of the Double-Lined Binary HD 1383T.S.Boyajian,D.R.Gies 1,M.E.Helsel 2,A.B.Kaye 1,M.V.McSwain 1,3,4,R.L.Riddle 1,5,D.W.Wingert 1Center for High Angular Resolution Astronomy and Department of Physics and Astronomy,Georgia State University,P.O.Box 4106,Atlanta,GA 30302-4106;tabetha@,gies@,marian.helsel@,anthony.kaye@,mcswain@,riddle@,wingert@ ABSTRACT We present new results from a study of high quality,red spectra of the massive binary star system HD 1383(B0.5Ib +B0.5Ib).We determined radial veloci-ties and revised orbital elements (P =20.28184±0.0002d)and made Doppler tomographic reconstructions of the component spectra.A comparison of these with model spectra from non-LTE,line blanketed atmospheres indicates that both stars have almost identical masses (M 2/M 1=1.020±0.014),temperatures (T eff=28000±1000K),gravities (log g =3.25±0.25),and projected rotational velocities (V sin i 30km s −1).We investigate a number of constraints on the radii and masses of the stars based upon the absence of eclipses,surface grav-ity,stellar wind terminal velocity,and probable location in the Perseus spiral arm of the Galaxy,and these indicate a range in probable radius and mass ofR/R ⊙=14−20and M/M ⊙=16−35,respectively.These values are consistentwith model evolutionary masses for single stars of this temperature and gravity.Both stars are much smaller than their respective Roche radii,so the systemis probably in a pre-contact stage of evolution.Afit of the system’s spectralenergy distribution yields a reddening of E(B−V)=0.55±0.05and a ratioof total-to-selective extinction of R=2.97±0.15.Wefind no evidence of Hαemission from colliding stellar winds,which is probably the consequence of thelow gas densities in the colliding winds zone.Subject headings:binaries:spectroscopic—stars:early-type—stars:evolution—stars:individual(HD1383)—supergiants—stars:winds,outflows1.IntroductionThe evolutionary paths of massive binaries depend critically on processes related to mass transfer and mass loss at the time when the initially more massive star begins tofill its Roche volume(Langer et al.2004;Petrovic,Langer,&van der Hucht2005).On the one hand,mass from the donor star may end up entirely in a rejuvenated mass gainer,but on the other hand a high mass transfer rate may cause the gainer to swell and bring the system into a common envelope phase,in which most of the donor’s mass is lost from the system entirely. Evidence of both outcomes is found among post-Roche lobe overflow systems(Langer et al. 2004;Petrovic et al.2005).We can better constrain the problem of the probable results of the interaction by studying binaries in an advanced evolutionary state just prior to Roche-filling.Those binaries of nearly identical masses are particularly interesting because we can usually observe the spectra of both components.Close pairs of nearly identical,evolved massive stars are quite rare.The HD1383system is the only such system found in Ninth Catalogue of Spectroscopic Binary Orbits(Pourbaix et al.2004)(with identical components of types B0.5Ib+B0.5Ib;Hill&Fisher1986).Another similar massive stellar system,HD152248,was previously classified as a O7I+O7I(Penny, Gies,&Bagnuolo1999),although a more thorough analysis by Sana et al.(2001)revised the classifications to O7.5III+O7III,deviating from the exact match of types found in HD1383.The HD152248system is eclipsing and the mass determinations made by Penny et al.(1999)and Sana et al.(2001)indicate that both stars are undermassive(by factors of 2and1.4,respectively,in the two studies)relative to the predicted evolutionary masses for single stars.Here we focus our attention on HD1383(BD+60◦25,HIP1466).The system was identified as a double-lined binary early on(Sanford&Merrill1938;Slettebak1956), but thefirst orbital elements were determined later by Hill&Fisher(1986)who found that the system consists of two nearly identical stars with an orbital period of20.3d.Morgan,Code,&Whitford(1955)originally adopted the system as a spectral standard for the B1II type,but Hill&Fisher(1986)revised the types slightly based upon detailed measurements of line equivalent widths of both components.The system is located in the sky in the vicinity of the Cas OB4association(Humphreys1978),which is located in the Perseus arm of the Galaxy.The star has played an important role in studies of the interstellar medium in this direction(see Cartledge et al.2004).Various distances have been estimated based upon the assumption that HD1383is a single,B1II star.Wakker et al.(1998)found a distance of 1.7kpc,which agrees well with Humphreys(1978)value of1.68kpc.Humphreys(1978) noted that HD1383might not be a member of the Cas OB4association,because the latter has a greater distance of2.88kpc.However,the fact that HD1383is a binary consisting of two stars with approximately equal brightness implies that it farther away from us than these previous estimates indicate and that it is closer to Cas OB4(Hill&Fisher1986offer a distance3.0kpc for HD1383).Here we present a study of a set of red spectra of HD1383that we obtained(§2)to re-analyze the orbital elements(§3)and to search for evidence of Hαemission related to colliding winds(Thaller1997;Sana et al.2001).We discuss the physical parameters of the stars from an analysis of their individual spectra obtained from a Doppler tomography reconstruction(§4).We then present a number of constraints on the radii and masses of the stars(§5)that lead us to conclude that both stars have radii smaller than their Roche radii and luminosities that are too small to power strong winds(explaining the lack of Hαemission from colliding winds).2.Observations and Radial VelocitiesThe optical spectra of HD1383were obtained with the Kitt Peak National Observatory 0.9m coud´e feed telescope during four observing runs between1999August and1999De-cember.Most of these spectra were obtained with the short collimator and grating RC181 (316grooves mm−1with a blaze wavelength of7500˚A;made infirst order with a GG495filter to block higher orders),which yielded an average resolving power of R=λ/δλ=4000 (see Gies et al.2002a for details of each observing run).The last four spectra were made with grating B(632grooves mm−1with a blaze wavelength of6000˚A in second order)and these have a much higher resolving power,R=λ/δλ=21300.Exposure times varied from 20to30minutes.These spectra all cover a common spectral range between6456˚A and 6728˚A,and they generally have a S/N≈340pixel−1in the continuum.The spectra wereextracted and calibrated using standard routines in IRAF6,and then each continuum rec-tified spectrum was transformed onto a uniform heliocentric wavelength grid for analysis. Atmospheric telluric lines were removed by division of modified versions of spectra of the rapidly rotating A-starζAql that we also observed(Gies et al.2002a).We measured radial velocities for HD1383using a templatefitting method(Gies et al. 2002b).The red spectrum of HD1383has few lines in the region observed.Hαwas not used in the radial velocity analysis because it is too broad and the components are generally blended.The lines of C IIλλ6578,6582and O IIλλ6641,6721are very weak and difficult to measure in individual spectra.Thus,we focused on the remaining,problem-free line of He Iλ6678for this radial velocity study.The individual component lines are quite narrow, symmetric,and comparable in shape to the instrumental broadening function,so we chose to represent each component’s profile as a Gaussian function.We selected appropriate shape parameters byfitting Gaussians to the best separated profiles of He Iλ6678,and we used the average values of the parameters to create separate Gaussian absorption line profiles to represent both the primary and secondary stars.We also obtained preliminary orbital veloc-ity curves based upon the Gaussianfits of the well separated spectra,and these were used to estimate the approximate velocities for all the times of observation.We then determined radial velocities for both components in all of our spectra by a non-linear,least-squaresfit of the composite profiles,and our results are collected in Table1,which lists the heliocentric Julian date of mid-exposure,orbital phase from the solution for the primary component, and the observed velocity plus the residual from thefit(observed minus calculated)for both components.3.Orbital Elements of HD1383Hill&Fisher(1986)found that HD1383is a double-lined spectroscopic binary with a period of20.2819days.We combined our radial velocities(Table1)with the compilation of radial velocity measurements from Hill&Fisher(1986)for a total101and77radial velocity measurements(spanning75y)of the primary and secondary components,ing a’dirty’discrete Fourier transform and CLEAN deconvolution algorithm(Roberts,Leh´a r, &Dreher1987),we constructed power spectra for both the primary and secondary using the time series of radial velocity measurements for each.The strongest signal in the powerspectra occurs at P=20.3days,which we then used as a starting value for the following orbital solutions.We used the non-linear,least-squaresfitting program from Morbey&Brosterhus(1974) to determine orbital elements.We found that our derived velocities were swapped between the primary and secondary for two observations when the components were thoroughly blended,and we assigned zero weight to these measurements in our orbitalfit.First,we determined the period of the primary and secondary independently using all the data avail-able,and then we determined a mean value of P=20.28184±0.00020d,which wefixed for both stars in the subsequent orbital solutions for HD1383.Then only the new radial velocity data presented in this paper were used to calculate independent orbital elements for the primary and secondary stars.The separate results for the primary and secondary are presented in Table2together with the original results from Hill&Fisher(1986),and the radial velocity curves and observations are plotted in Figure1.Wefind that the orbital elements for the primary and secondary are mainly consistent with each other and with the original determinations by Hill&Fisher(1986)with two interesting exceptions.First,the star identified as the“primary”by Hill&Fisher(1986)turns out to be the lower mass object in our solution because of a slight revision in the semiamplitudes.Rather than introducing more confusion about the stars’identities,we will retain the labels of primary and secondary given by Hill&Fisher(1986).Second,wefind that the eccentricity derived for the primary is approximately3σdifferent from that obtained for the secondary.Furthermore,the longitude of periastron values are suspiciously close to0◦and180◦,which suggests that the velocity curves may be distorted by subtle emission effects from circumstellar gas(the possible origin of the non-uniform distribution of longitude of periastron among massive binaries known as the Barr Effect;Batten&Ovenden1968;Fracastoro1979;Howarth1993).Given these difficulties,we decided not to force a joint solution with a common geometry and systemic velocity.4.Tomographic Reconstruction and Stellar ParametersOnce the orbital solution was found for HD1383,we used a tomographic reconstruction technique(Bagnuolo et al.1994)to separate the two individual spectra of the system.The method of tomographic reconstruction uses all the combined spectra and their associated radial velocities to determine the appearance of each star’s spectrum.The monochromatic flux ratio of the primary to the secondary was assumed to be1.0(Hill&Fisher1986). The ISM lines were removed from each spectrum prior to reconstruction to avoid spurious reconstructed features in their vicinity.Figure2shows a plot of the reconstructed spectrawith identifications of the principal lines.The two spectra are remarkably similar in the red spectral region.We made estimates of the effective temperatures,gravities,and projected rotational velocities through a comparison with model spectra from the codes TLUSTY and SYN-SPEC(Hubeny1988;Hubeny&Lanz1995;Hubeny,Heap,&Lanz1998).Lanz&Hubeny (2003)presented a grid of model spectra for O-type stars that use line blanketed,non-local thermodynamic equilibrium,plane-parallel,hydrostatic atmospheres,and fortunately,these models extend to cool enough temperatures(27500K)to be applicable to the the stars in HD1383.These models adopt afixed microturbulent velocity of10km s−1,a value which is appropriate for B-supergiants(Gies&Lambert1992).These models were also used by Dufton et al.(2005)in their spectral analysis of B-supergiants in the SMC.The projected rotational velocity,V sin i,for each star was measured by comparing the observed FWHM of an absorption line with that for model profiles for a range in assumed V sin i.The rotationally broadened profiles were calculated by a simple convolution of the zero-rotation model profiles with a rotational broadening function(Gray1992)using a linear limb darkening coefficientǫ=0.220(from the tabulated value for T eff=30000K,log g=3.0, andλ=6975˚A from Wade&Rucinski1985).The derived projected rotational velocities based upon the He Iλ6678profile are V sin i=76±6and72±6km s−1for the primary and secondary,respectively,in good agreement with the estimate of75±5km s−1for both stars from measurements of blue spectral lines by Hill&Fisher(1986).However,the weaker C II λλ6578,6582lines are distinctly narrower and their mean projected rotational velocities are V sin i=32±18and26±18km s−1for the primary and secondary,respectively(almost unresolved at our spectral resolution).Ryans et al.(2002)argue that the line broadening of B-supergiants is probably dominated by macroturbulence,so that the measured broadening only provides an upper limit on the actual rotational velocity.They alsofind a trend for stronger lines(like He Iλ6678)to display greater broadening than weaker lines(like C II λλ6578,6582),perhaps due to an increase in turbulent broadening with height in the at-mosphere.Thus,the true projected rotational velocities of the components of HD1383are probably less than≈30km s−1.We then compared rotationally broadened versions of the model solar abundance spectra from Lanz&Hubeny(2003)directly with the reconstructed spectra to estimate temperatures and gravities.The best matches were found with T eff=28000±1000K and log g=3.25±0.25 for both stars,and the model spectra for these parameters are shown in Figure2as dotted lines.This spectral region contains a number of features that are particularly sensitive to temperature and gravity.For example,at hotter temperatures the C II,O II,and He I lines weaken while new lines of Si IVλλ6667,6701and He IIλ6683appear that are clearly absentin the reconstructed spectra of HD1383.On the other hand,at cooler temperatures the C II doublet increases greatly in strength and the N IIλ6610linefirst appears(again absent in the reconstructed spectra).The wings of the Hαline provide a diagnostic of the gravity(wider due to greater linear Stark broadening in higher gravity models).We caution that the core of Hαappears to befilled in with residual emission from the stellar wind,and the TLUSTY models we used are based upon static atmospheres that do not account for wind outflow. However,we expect that the wind effects will be mainly confined to the higher opacity line core in relatively weak-wind stars like those in HD1383and that the gravity derived from the pressure-broadened line wings will be close to(or slightly less)than the actual gravity(see the discussion about the Hγline wings in Puls et al.1996).The observed C II lines appear to be somewhat weaker than predicted in the best matching model spectrum,which may reflect an underabundance of C caused by mixing of CNO-processed gas into the atmosphere. McErlean,Lennon,&Dufton(1999)also observed this effect in other B-supergiants.They give modelfitting results for two galactic B0.5Ib stars,HD192422and HD213087,and their derived temperatures and gravities are in reasonable agreement with our adopted values for HD1383.We found that the generally good match between the model and observed spectra indicates that the monochromaticflux ratio is1.0±0.1.5.DiscussionWe can use our results to place some general constraints on the evolutionary status of the binary system.These various limits are summarized in a radius–mass diagram for the secondary star shown in Figure3(the corresponding diagram for the primary would appear almost the same).The system is not a known eclipsing binary,and we confirmed the lack of eclipses(or any other orbital phase-related variations)by plotting the available photometry from Hipparcos(Perryman1997)as a function of orbital phase.If we assume that the stars have the same radius R(as indicated by their temperatures and the observedflux ratio), then the upper limit on the orbital inclination i set by the lack of eclipses is found fromtan i=a sin i1+e cosν.(1)We considered both conjunctions,ν=90◦−ωand270◦−ω2,with the derived eccentricities for the primary and secondary tofind the minimum inclination for a given radius and hence a lower limit on the mass of the secondary from M2sin3i(Table2),and the resulting radius–mass relationships are plotted as dashed lines in Figure3.The acceptable solution space is restricted to the region above these lines(at lower i).The next constraint comes from the gravity determination found byfitting the Hαline wings,and the solid lines in Figure3show the relations for log g=3.25±0.25.If weak stellar wind emission is biasing this measurement,then the actual log g may be somewhat larger than our estimate.We can use the stellar wind properties tofind additional limitations.Theoretical and observational studies of the winds of massive stars show that the wind terminal velocity v∞is generally proportional to the escape velocity v esc among stars of comparable temperature (Prinja,Barlow,&Howarth1990;Lamers,Snow,&Lindholm1995;Kudritzki&Puls2000; Evans et al.2004;Crowther,Lennon,&Walborn2006).Prinja et al.(1990)have made the most complete study of this relationship among the B-supergiants,and theyfind that v∞=(1.96±0.60)v esc for B0-B3I stars.We measured the terminal velocity to be v∞= 1100±120km s−1according to the short wavelength absorption minimum point in the profile of the C IVλ1550P Cygni line in a high dispersion spectrum of HD1383from the archive of the International Ultraviolet Explorer Satellite(made at orbital phaseφ=0.21, near conjunction).This terminal velocity is somewhat lower than the mean for the B0.5 supergiants of1405km s−1but it is well within the range of terminal velocities for this group(Prinja et al.1990).We show the resulting radius–mass functions from the mean and ±1σlimits of the v∞/v esc relation in Figure3(triple dot-dashed line).Note that the larger values of this ratio found in recent studies(Evans et al.2004;Crowther et al.2006)are probably more appropriate for much more luminous stars and would lead to unrealistically large radii in the case of HD1383.Finally,we can obtain one more constraint by considering the radius–distance rela-tionship that is established fromfits of the reddened stellarflux distribution.We show in Figure4the observed spectral energy distribution for HD1383based upon low dispersion UV spectroscopy from IUE,Johnson U,B,V magnitudes(Haug1970;Colina,Bohlin,&Castelli 1996),and2MASS J,H,K infrared magnitudes(Cohen,Wheaton,&Megeath2003;Cutri et al.2003).Wefit thisflux distribution using a model spectrum from Lanz&Hubeny (2003)for two identical stars of T eff=28000K and log g=3.25,which we transformed using the Galactic extinction curve from Fitzpatrick(1999).The bestfit parameters for the extinction curve are a reddening of E(B−V)=0.55±0.05and a ratio of total-to-selective extinction of R=2.97±0.15.The normalization of the model spectrum yields the limb darkened angular diameter of one star,θLD=54±7microarcsec,and therefore the stellar radius is related to the distance d(measured in kpc)byR/R⊙=(5.8±0.8)d.(2) The binary is too distant to obtain a reliable parallax from Hipparcos measurements (Schr¨o der et al.2004).Our view through the plane of the Galaxy in the direction of HD1383 (l=119.◦02,b=−0.◦89)traversesfirst the nearer Perseus arm(d=2.4−3.5kpc)and then the more distant Cygnus arm(d 3.9kpc)(Kimeswenger&Weinberger1989;Negueruela&Marco2003).We suspect that HD1383resides in the closer Perseus arm.It is very close in the sky to BD+60◦39(spectral classification of O9V),which has an identical reddening and which Garmany&Stencel(1992)assign to the Cas OB4association(at a distance of 2.8kpc).There is a considerable amount of differential Galactic rotation along this line of sight,and we can estimate at what distance the systemic velocity of the binary matches the expected radial velocity difference between the Sun and the remote local standard of rest. We used the procedure described by Berger&Gies(2001)tofind the distance–radial velocity relation along this line of sight,and the binary’s systemic velocity places it at a distance of3.2kpc(although if we allow a±10km s−1deviation in motion from the local standard of rest,then the acceptable range is between2.3and4.2kpc).Both lines of evidence are consistent with a location in the Perseus arm,and we have plotted the corresponding stellar radius range as a solid line in the bottom of Figure3.The combination of all these constraints indicates that the parameter ranges are prob-ably R/R⊙=14−20and M/M⊙=16−35.This range is consistent with the masses predicted by single star evolutionary tracks for the temperature and gravity of the compo-nents in HD1383(illustrated in Figure3as a dotted line,from the evolutionary tracks for non-rotating,solar metallicity stars of T eff=28000K;Schaller et al.1992).The radii are much smaller than the Roche lobe radii(approximately44R⊙for masses of25M⊙),so the system is probably still observed in a pre-contact phase in which both stars have evolved like single objects.We originally selected HD1383as a possible target for exhibiting Hαemission from colliding winds(Thaller1997).However,our spectra show no obvious signs of such Hαemission.We show in Figure5the Hαprofiles arranged as a function of orbital phase,and the variations appear to be entirely consistent with the motion of the photospheric Hαlines of both components.Sana et al.(2001)found evidence of a weak,broad,and stationary Hαemission feature in their spectra of the similar colliding winds binary HD152248,and they argue that the emission forms in a planar collision zone between the stars.The lack of Hαcolliding winds emission in the spectrum of HD1383is probably due to three significant differences between these binary systems.First,the mass loss rates are lower in HD1383 compared to HD152248.We can estimate approximately the mass loss rates using the wind momentum relation for hot stars,log(˙Mv∞(R/R⊙)1/2)=log D0+x log(L/L⊙)(3) where D0and x are constants and L is the stellar luminosity(Kudritzki&Puls2000;Vink, de Koter,&Lamers2000).If we adopt T eff=28000K,R/R⊙=14−20,and v∞=1100 km s−1,then the predicted mass loss rate is log˙M=−6.3±0.4(units of M⊙y−1)according to the model of Vink et al.(2000),which is about six times lower than the mass loss ratesof the stars in HD152248(Sana et al.2004).Second,the binary separation is about twice as large in HD1383compared to HD152248(Sana et al.2004),and hence the wind density in the regions near the collision zone will be much lower.Third,the collision zone itself may cool less efficiently and may avoid the formation of high density gas fragments that are predicted to occur according to hydrodyanmical simulations of the winds of HD152248 (Sana et al.2004).Stevens,Blondin,&Pollock(1992)show how the gas dynamics of the colliding winds zone depends on the ratio of the cooling timescale to the gasflow timescale,χ≈v48d12/˙M−7,where v8is the wind velocity in units of1000km s−1,d12is the distance from the star to the contact surface in units of107km,and˙M−7is the mass loss rate in units of10−7M⊙y−1.This ratio is about1.1for HD1383,indicating that the collision zone remains hot over dimensions comparable to those of the binary system(an adiabatic wind zone),but the ratio is much smaller(0.1)in the case of HD152248where efficient cooling (in a radiative colliding wind)leads to the fragmentation of the shock front into knots of cool gas(Sana et al.2004).Since Hαemission is a recombination process that depends on the square of the gas density and since the colliding wind density will be much lower in HD1383compared to HD152248for all of the reasons outlined above,the apparent lack of Hαemission in the spectrum of HD1383is not surprising.Our results indicate that HD1383is a wide enough system that the components have avoided direct interaction or mass exchange.According to the models of Schaller et al. (1992),this state may last for another0.5Myr(for masses of25M⊙).However,after that time both stars will quickly grow in radius and reach contact within the last104y before they explode as supernovae.Their brief interaction phase then may result in a common envelope stage leading to a shorter period system containing an O-supergiant and neutron star(like the massive X-ray binary system HD153919/4U1700–37;Ankay et al.2001)or in a wider binary consisting of a rapidly evolving B-A supergiant transferring mass at a tremendous rate to a collapsed companion surrounded by a super-Eddington accretion disk(like SS433; Hillwig et al.2004).Either way,HD1383is destined to become an extraordinarily energetic interacting binary for a brief instant in the Galaxy’s future.We thank Daryl Willmarth and the staffof KPNO for their assistance in making these observations possible.We are also grateful to the referee,Dr.Hughes Sana,for his insight and helpful comments on this study.This work was supported by the National Science Foundation under Grant No.AST-0205297.Institutional support has been provided from the GSU College of Arts and Sciences and from the Research Program Enhancement fund of the Board of Regents of the University System of Georgia,administered through the GSU Office of the Vice President for Research.REFERENCESAnkay,A.,Kaper,L.,de Bruijne,J.H.J.,Dewi,J.,Hoogerwerf,R.,&Savonije,G.J.2001, A&A,370,170Bagnuolo,W.G.,Jr.,Gies,D.R.,Hahula,M.E.,Wiemker,R.,&Wiggs,M.S.1994,ApJ, 423,446Batten,A.H.,&Ovenden,M.W.1968,PASP,80,85Berger,D.H.,&Gies,D.R.2001,ApJ,555,364Cartledge,S.I.B.,Lauroesch,J.T.,Meyer,D.M.,&Sofia,U.J.2004,ApJ,613,1037 Cohen,M.,Wheaton,W.A.,&Megeath,S.T.2003,AJ,126,1090Colina,L.,Bohlin,R.,&Castelli,F.1996,HST Instrument Science Report CAL/SCS-008 (Baltimore:STScI)Crowther,P.A.,Lennon,D.J.,&Walborn,N.R.2006,A&A,446,279Cutri,R.M.,et al.2003,The2MASS All-Sky Catalog of Point Sources(Pasadena: IPAC/Cal.Inst.Tech.)Dufton,P.L.,Ryans,R.S.I.,Trundle,C.,Lennon,D.J.,Hubeny,I.,Lanz,T.,&Allende Prieto,C.2005,A&A,434,1125Evans,C.J.,Lennon,D.J.,Trundle,C.,Heap,S.R.,&Lindler,D.J.2004,ApJ,607,451 Fitzpatrick,E.L.1999,PASP,111,63Fracastoro,M.G.1979,A&A,78,112Garmany,C.D.,&Stencel,R.E.1992,A&AS,94,211Gies,D.R.,&Lambert,D.L.1992,ApJ,387,673Gies,D.R.,McSwain,M.V.,Riddle,R.L.,Wang,Z.,Wiita,P.J.,&Wingert,D.W.2002a,ApJ,566,1069Gies,D.R.,Penny,L.R.,Mayer,P.,Drechsel,H.,&Lorenz,R.2002b,ApJ,574,957 Gray,D.F.1992,The Observation and Analysis of Stellar Photospheres(2nd ed.)(Cam-bridge:Cambridge Univ.Press)。
