Assisted hatching (AH) is a manipulation of zona pellucida aiming to facilitate embryo implantation.
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小学上册英语第1单元真题(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 A solute can be a _______ or a liquid.2 My grandfather tells __________ (有趣的) jokes.3 Which month has 28 days?A. All of themB. JanuaryC. FebruaryD. April答案: C4 I enjoy ______ at the beach.5 I can ______ (应对) pressure when studying.6 The _____ is the second planet from the sun.7 I can ______ (使用) technology for school projects.8 What is the main ingredient in guacamole?A. AvocadoB. TomatoC. PepperD. Onion答案: A9 We have a _____ (假期) planned for winter.10 She is wearing ___. (gloves)11 My birthday is in _____ (May/Wednesday).12 The toucan's beak is large and colorful, aiding in attracting ________________ (配偶).13 My favorite animal is a ______ (猴子) because they are funny.14 How many legs does a dog have?A. 2B. 3C. 4D. 515 The force that pulls objects toward the Earth is known as ______.16 A reaction that absorbs heat is called an ______ reaction.17 During summer vacation, I plan to __________ with my family. We might go to__________ or spend time at __________. I am excited about all the adventures we will have!18 We will _______ (一起去) the zoo.19 I call my friend “.”20 A _____ (小马) often enjoys being pampered.21 I enjoy _____ (tasting) different herbs.22 A __________ is a substance that cannot be broken down into simpler substances.23 The ______ is a popular author.24 A ______ is a small animal that is often kept as a pet.25 The butterfly flaps its wings ______ (优雅).26 _____ (春天) is when many plants start to bloom.27 A __________ is a large city that is the center of government.28 What is the term for the study of weather?A. AstronomyB. MeteorologyC. GeologyD. Biology答案:B29 What is the main function of roots in a plant?A. To produce flowersB. To absorb waterC. To make foodD. To support the stem答案: B30 The capital of Canada is __________.31 The chemical symbol for zinc is ______.32 What do we call a baby chicken?A. DucklingB. CalfC. ChickD. Lamb33 The element with the symbol Cl is __________.34 My _____ (阳台) has colorful flowers.35 recycling program) reduces waste. The ____36 The __________ is a region known for its tropical climate.37 I can build anything with my ________ (玩具).38 We visit the ______ (科技馆) to learn about robots.39 My sister enjoys learning about ____ (geography).40 A rabbit can see well in ______ (黑暗).41 The puppy is very ___. (playful)42 The process of photosynthesis converts sunlight into _______ energy.43 I bought a new _____ (毛绒玩具) that looks like a puppy. 我买了一个新的毛绒玩具,看起来像小狗。
小学上册英语第6单元真题[含答案]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 __________ (人际关系) are important for happiness.2.What do we call a scientist who studies the atmosphere?A. MeteorologistB. ClimatologistC. Environmental ScientistD. Geochemist3.The Earth's crust is divided into large sections called ______ plates.4.They are going to a ________.5. A ____(land use) survey assesses how land is used.6.My aunt is a ______. She loves to teach children.7.The ______ (温室) helps plants grow in winter.8.The ________ is a famous desert in Africa.9.I like to go ______ (远足) to enjoy the beauty of nature.10.Which animal is known as the king of the jungle?A. TigerB. LionC. BearD. Elephant11._____ (pruning) helps plants grow better.12.The __________ (树) grows tall and strong in the forest.13. A ______ (园丁) enjoys working with soil.14.Which of these is a winter sport?A. SoccerB. SwimmingC. SkiingD. Basketball答案:C15. A _____ (bouquet) of flowers makes a lovely gift.16. A __________ (色素) gives color to plants and flowers.17.My sister has a pet ______ (鹦鹉) that talks.18.plate tectonics) theory explains earthquakes. The ____19.The ________ (乡村) is peaceful and quiet.20.The ______ (狼) howls at the moon.21.The process of fermentation converts sugar into ______.22. A displacement reaction involves one element replacing ______.23.The process of distillation separates liquids based on their _____.24.My dog likes to dig in the ______ (沙子).25.What is the color of a typical blueberry?A. GreenB. BlueC. RedD. Purple答案:B26.My brother is a ______. He enjoys drawing.27.I enjoy watching the ______ (日出) in the morning.28.The chemical formula for cyclopentane is ______.29.Which animal is known for its wisdom?A. OwlB. EagleC. ParrotD. Crow答案:A30.Neutrons have no ______ charge.31.What is the largest mammal in the world?A. ElephantB. Blue WhaleC. GiraffeD. Hippopotamus答案:B32.I like to ______ (参加) workshops.33.My cousin is a ______. She enjoys traveling to new countries.34.The ______ (小鱼) swims gracefully through the coral reef.35.What do you call a young squirrel?A. KitB. PupC. KittenD. Baby36.The atomic number of an element is determined by the number of ______ it has.37. A ____(sustainable city) prioritizes balance between nature and urban life.38.What sound does a cow make?A. MeowB. BarkC. MooD. Quack39.I want to ________ (learn) a new language.40.I enjoy writing letters to my _______ (朋友) who live far away. It keeps our friendship strong.41.The ancient Greeks are famous for their _______ and philosophy.42.The sky is _______ (阴暗的) today.43.The jackal is a clever ______ (动物).44._______ can grow in both sunny and shady places.45.Which of these is a basic shape?A. CircleB. OctagonC. HexagonD. Rhombus46.The chemical formula for sodium sulfate is ______.47.The ______ (田野) is full of blooming flowers.48.The girl sings very ________.49.What do you call the food that comes from cows?A. BreadB. CheeseC. ChickenD. Fish答案:B50.What do we call a set of instructions for a computer?A. ProgramB. SoftwareC. ApplicationD. Code答案:D51.The chemical formula for iodine monochloride is _______.52.The owl can turn its head almost _______ (完全) around.53.The anteater has a long ________________ (舌头).54. A ______ is a type of reaction that involves heat.55.What is the capital of Finland?A. TallinnB. OsloC. HelsinkiD. Stockholm答案:C Helsinki56.My grandfather tells me interesting ________ (故事) about his childhood. I listen carefully and ask him many ________ (问题).57.What is the name of the famous tower in Paris?A. Leaning Tower of PisaB. Burj KhalifaC. Eiffel TowerD. Empire State Building答案:C58.My cat loves to play with _______ (毛线).59.The __________ was so bright that I had to wear sunglasses. (阳光)60.The ______ (海龟) lays eggs on sandy beaches.61.What is the name of the plant that is known for its medicinal properties?A. FernB. Aloe VeraC. CactusD. Moss答案:B62.The dog is _____ (barking/sleeping) in the yard.63.The butterfly emerges from its _____ chrysalis.64.I want to learn to _____ (swim/fly).65.ts can grow from __________ (切割). Some pla66.After school, I play video games with my ________ (朋友) online. It’s so much ________ (乐趣).67.The butterfly starts as a ______.68.The process of oxidation involves __________ losing electrons.69.I can ______ (清楚地表达) my ideas.70.The ant is very _______ (团结) with its colony.71.The clock shows _____ (ten/twelve).72. A compound is formed when two or more different ______ combine.73.The ________ (地理学) is fascinating to study.74.How many players are on a polo team?A. 4B. 5C. 6D. 775.My favorite color is ______ (red).76.What is the opposite of 'big'?A. HugeB. SmallC. TallD. Large77.What is the capital of Iceland?A. ReykjavikB. AkureyriC. SelfossD. Keflavik答案:A78. A rabbit’s teeth are always ______ (生长).79.The wind is _______ (blowing) through the trees.80.The penguin waddles on ________________ (冰).81.What is the name of the famous clock tower in London?A. Big BenB. Eiffel TowerC. Leaning Tower of PisaD. Burj Khalifa82.The eagle flies high in the _________. (天空)83.Which fruit is yellow?A. AppleB. BananaC. CherryD. Grape答案:B84.The __________ (海洋生物) are fascinating to study.85.He _____ (plays/played) video games all day.86.We have a ______ (特别的) event this weekend.87.The octopus has three ______ (心脏).88.I can _____ (跳舞) well.89.The owl is active at ______.90. A strong acid can corrode ______ materials.91.I like _____ (旅行) with my family.92.What do you call a person who makes bread?A. BakerB. ChefC. CookD. Caterer答案:A93.The __________ (大西洋奴隶贸易) was a dark part of history.94. A diatomic molecule consists of two atoms of the _____ element.95.Which season is known for blooming flowers?A. WinterB. SpringC. SummerD. Fall答案:B96. A chemical reaction that releases light is called a _______ reaction.97.The ____ is a friendly animal that loves to be petted.98.What is the name of the famous artist known for his sculptures?A. MichelangeloB. RembrandtC. Van GoghD. Renoir答案:A99.What is the capital of Greece?A. AthensB. ThessalonikiC. CreteD. Rhodes100.What is the name of the famous detective created by Arthur Conan Doyle?A. Sherlock HolmesB. Hercule PoirotC. Miss MarpleD. Sam Spade。
小学上册英语第四单元综合卷英语试题一、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.How many sides does a square have?A. 2B. 3C. 4D. 52.She is wearing a ___ (yellow/blue) hat.3.What do we call a person who designs buildings?A. ArchitectB. EngineerC. ConstructorD. Developer4.What do caterpillars become?A. BeesB. ButterfliesC. MothsD. Spiders5.What do you call the person who fixes cars?A. BakerB. MechanicC. TeacherD. DoctorB6.The girl loves to ________.7.The __________ (历史的挑战者) question established narratives.8.My friend, ______ (我的朋友), has a pet rabbit.9.My grandmother makes the best __________. (果酱)10.The fish is _____ around the tank. (swimming)11.The country famous for its opera houses is ________ (澳大利亚).12.The tree is ___ (bushing/barren).13.The __________ is a famous historical site in Egypt. (金字塔)14.The _____ (小羊) bleats softly as it grazes in the field. 小羊在田野里吃草时轻声叫唤。
英语科普环保类阅读试题答案及解析1. February 16, 2014(VOA)JAKARTA — The United States and China say they recognize the need for "urgent action" to address the twin challenges of climate change and the air pollution caused by burning fossil fuels. U.S. Secretary of State John Kerry called for greater political will to address a warming planet.China is the leading producer of greenhouse gases and joins the United States as the largest consumers of energy. So U.S. officials say the world's two biggest economies agreeing to limit emissions and promote energy efficiency in buildings and industry "sends a strong message to the world" that this is an issue that needs to be addressed now.Following that agreement with Chinese leaders, Secretary Kerry told an audience in Indonesia that Washington hopes this "unique partnership" with Beijing will help set an example for global leadership and global seriousness on climate change.Kerry Warns About Global Climate Change"Together we account for roughly 40 percent of the world’s emissions. But this is not just about China and the United States," Kerry said. "It is about every country on Earth doing whatever it can to pursue cleaner and healthier energy sources.Kerry said scientific evidence compels the world to act."It is not a lack of ability that is the problem," Kerry said. "It is a lack of political resolve that is standing in our way.The European Union is calling for a 40 percent cut in carbon emissions by 2030. European Commission President Jose Manuel Barroso says that target is ambitious and affordable."It shows that we are beyond debate where we either have to be green or a defender of industry," Barroso said. "We believe these two issues are not contradictory, but can perfectly go together if handled smartly.Some European parliamentarians and some environmentalists believe the carbon reduction goals do not do enough to encourage cleaner energy. Jason Anderson heads European climate and energy policy for the World Wildlife Fund."We want to make sure that they do not put the brakes on the energy transition that we are seeing now," Anderson said. "Their ambitions for renewable energy would actually slow down the pace of change, which it is completely senseless as it is one of those areas of the economy that is growing right now.Kerry's climate speech was the first in a series of events meant to focus on cutting carbon emissions before talks in Paris next year on coming up with a successor to the 1997 Kyoto Protocol, which was never ratified by the United States. ()419【1】European Commission President Jose Manuel Barroso believes that________.A.The European Union accounts for 40 percent of the world’s emissions.B.we either have to be green or a defender of industry.C.we have to be green and a defender of industry if handled smartly.D.the carbon reduction goals do not do enough to encourage cleaner energy.【答案】C【解析】考查细节理解。
小学上册英语第1单元真题英语试题一、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 capital of Grenada is __________.2.The ______ (植物的特征) can inform garden design.3.The flowers smell _______ (香).4.What do we call the area of land that is surrounded by water?A. IslandB. PeninsulaC. CoastD. Shore5.What do bees make?A. MilkB. HoneyC. JamD. Butter6. A _______ is a substance that can accept protons in a reaction.7.The _____ (bus) is coming soon.8.What do you call the process of plants making their own food?A. DigestionB. PhotosynthesisC. RespirationD. GerminationB9.What is the capital of Uzbekistan?A. TashkentB. SamarkandC. BukharaD. FerganaA Tashkent10.My sister has a pet ______ (兔子) named Fluffy.11.What do we call the season when it rains a lot?A. SummerB. WinterC. SpringD. Autumn12.The cat is _____ on the couch. (lying)13.The first Olympic Games were held in ________ (古希腊).14.Which instrument is played by blowing air into it?A. GuitarB. DrumsC. FluteD. Piano15.The fall of the Roman Empire was a turning point in ________ (历史).16.My turtle is very _______ (温和).17.In _____ (越南), pho is a traditional dish.18.The process of evaporation can lead to __________ of solutions.19.What is the name of the famous fictional detective created by Arthur Conan Doyle?A. Hercule PoirotB. Sam SpadeC. Sherlock HolmesD. Miss MarpleC Sherlock Holmes20.My dad provides __________ (指导) when I need it.21.The process of separating mixtures based on their boiling points is called _______.22.What do you call a young meerkat?A. KitB. PupC. CalfD. Cub23.Which animal is known for its long tail and swinging from trees?A. DogB. CatC. MonkeyD. ElephantC24.I have _______ (many) friends at school.25.The __________ is where the Earth's crust is thinnest.26.How many players are on a badminton team?A. 2B. 3C. 4D. 527.Evaporation is a type of ______ change.28. A ______ is a nocturnal animal.29.I find ________ (天文学) very interesting.30.I like to feel the __________ on my skin during a sunny day. (阳光)31.The rabbit's favorite food is ________________ (胡萝卜).32.What is the common name for the disease caused by a lack of vitamin C?A. ScurvyB. RicketsC. AnemiaD. FluA33.What do we call a scientist who studies the atmosphere?A. MeteorologistB. GeologistC. ChemistD. BiologistA34.Which fruit is often mistaken for a vegetable?A. StrawberryB. TomatoC. LemonD. PeachB35.The butterfly goes through a ______ (变形) phase.36.The _______ (The Cold War) was characterized by a struggle for global influence.37.What do we call the study of the earth and its features?A. GeographyB. GeologyC. EcologyD. MeteorologyA38.I can _____ (讲) stories.39.The capital of Brunei is __________.40.Oxygen is essential for ______.41. A ________ (温泉) is a natural hot spring.42.My friend is very __________ (勤奋的).43.They are _____ (collecting) seashells.44.My favorite game is _____ (chess/football).45.What type of animal is a frog?A. MammalB. ReptileC. AmphibianD. Fish46.The Earth's crust is rich in ______ materials.47.What is the opposite of fast?A. QuickB. SlowC. SpeedyD. Rapid48.What is the term for a story that teaches a lesson?A. FableB. MythC. LegendD. NovelA49.Brazil is famous for its _____ (47) during Carnival.50.The badger is known for its digging ______ (能力).51.The __________ (历史的叙述风格) influence interpretation.52. A ______ is a geographical feature that attracts scientists.53.The process of sedimentation separates solids from ______.54.The trees in the _______ provide shade and a place to rest.55.The hedgehog rolls into a _________. (球)56.What do we call the act of managing finances?A. BudgetingB. AccountingC. InvestingD. PlanningA57.I have a toy _______ that can move its arms and legs.58.What is the name of the famous volcano in Italy?A. Mount EverestB. Mount FujiC. Mount VesuviusD. Mount KilimanjaroC59.Which planet is known as the Red Planet?A. EarthB. MarsC. JupiterD. Venus60.Respiration is a process that occurs in ________.61.I like to ______ (参与) in community events.62.What is the main ingredient in a Caesar salad?A. Romaine lettuceB. SpinachC. KaleD. Arugula63.I enjoy cooking ______ (美味) meals for my family.64. A llama can carry _______ (重物).65.The __________ (峭壁) overlooks the sea.66.The ancient Egyptians worshipped gods like ______ (拉) and ______ (伊西斯).67.Which of these is a type of tree?A. RoseB. OakC. DaisyD. SunflowerB68.The puppy is __________ and cute.69.The weather is ______ (sunny) today.70. A __________ is formed by the melting of glaciers.71.The __________ was a significant event in the fight for women's suffrage. (选举权运动)72.What is the opposite of hot?A. ColdB. WarmC. SunnyD. CoolA73.The __________ was a series of wars fought in the Middle Ages. (十字军东征)74.I play _____ (游戏) on my tablet.75.The cake smells _______ (甜美).76.The __________ (历史的探索旅程) promises discovery.77.The _______ can symbolize strength and resilience.78.The __________ is the process by which plants convert sunlight into energy.79.The park is very ________.80.What do you call a baby cat?A. PuppyB. KittenC. CubD. Chick81. A ______ (蛇) can be colorful and sometimes dangerous.82.What do you call the process of water falling from the sky?A. EvaporationB. PrecipitationC. CondensationD. CollectionB83.What do you call a baby cow?A. KittenB. CalfC. PuppyD. LambB84.What is the name of the famous clock tower in London?A. Big BenB. Eiffel TowerC. Leaning TowerD. Tower of PisaA85.The antelope runs very _________ (快).86.I like to ________ (听音乐) while studying.87.What is the capital city of Japan?A. BeijingB. SeoulC. TokyoD. BangkokC Tokyo88.What do we use to tell time?A. CalendarB. ClockC. MapD. ThermometerB89.I enjoy the smell of ______ (新鲜空气) after rain.90.What do you call the main character in a story?A. HeroB. VillainC. ProtagonistD. Antagonist91.My pet ___ (小仓鼠) sleeps in its cozy bed.92.The dog is _____ (barking/sleeping) in the yard.93.What do we call the study of the Earth's surface?A. GeographyB. GeologyC. AstronomyD. EcologyA94.My dad loves to go cycling in the ____ (park).95.Plants can be used to improve ______ (土壤质量).96.An example of a noble gas is _______.97.My sister plays the ____ (drums) in her school band.98.The atomic number tells you the number of ______ in an atom.99.I can learn about nature with my ________ (玩具名称).100.I love to ______ stories.。
小学上册英语第1单元期末试卷考试时间:90分钟(总分:140)B卷一、综合题(共计100题共100分)1. 听力题:The Earth's lithosphere is divided into tectonic ______.2. 选择题:What is the capital of Bangladesh?A. DhakaB. ChittagongC. KhulnaD. Rajshahi3. 听力题:My friend is very ________.4. 听力题:A ______ is a tool used to observe chemical reactions.5. 听力题:The baby is ________ in the crib.6. 填空题:A sunflower turns towards the _____.7. 听力题:The ______ helps kids learn to read.8. 听力题:The _____ (clock) shows the time.9. 选择题:How many legs does a dog have?A. TwoB. FourC. Six答案: B10. 听力题:The stars are out at ___. (night)11. 听力题:Tsunamis are caused by underwater ______ or volcanic eruptions.12. 填空题:I like eating ______ (苹果) because they are crunchy and ______ (健康).13. 选择题:What do we call a large body of salt water?A. RiverB. LakeC. OceanD. Pond答案:C14. 填空题:Planting flowers in clusters can create a stunning visual ______ in your garden. (成簇种植花卉可以在花园中创造出惊艳的视觉效果。
徐州2024年小学3年级英语第一单元期中试卷考试时间:100分钟(总分:140)A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:A ferret can scurry through tight ______ (空间).2、What sweet food is made from cocoa beans?A. CandyB. ChocolateC. CakeD. Ice cream答案:B3、听力题:The ______ is home to many fish.4、What do you call a place where you can buy food?A. LibraryB. Grocery storeC. MallD. Zoo答案:B5、听力题:We like to go _____ (钓鱼).6、填空题:My __________ (玩具名) is made of __________ (材料).7、What is the name of the story about a boy who never grew up?A. Alice in WonderlandB. Peter PanC. The Little MermaidD. Beauty and the Beast答案:B8、听力题:He is ________ (running) in the race.9、填空题:My ________ (老师) encourages us to do our best in school.10、What is the name of the famous explorer who sailed the ocean blue in 1492?A. Christopher ColumbusB. Ferdinand MagellanC. Vasco da GamaD. Hernán Cortés答案: A11、填空题:I have a toy _______ that can change colors.12、听力题:I like to watch ___. (movies)13、What is the capital of Egypt?A. CairoB. AlexandriaC. GizaD. Luxor答案: A14、填空题:My grandma makes the best ________ (汤) ever.15、听力题:A chemical formula shows the number and types of _____ in a compound.16、填空题:A _____ (草甸) is a grassy area with wildflowers.17、填空题:古代的________ (historians) 通过研究遗留物来了解过去。
小学上册英语第二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.I see a _____ balloon in the sky. (red)2.The _____ (花坛) can attract bees and butterflies.3.She is _______ (穿着) a blue hat.4.I love to visit ______ (科技中心) to see the latest inno vations. It’s fascinating to learn about advancements.5.The _____ (balloon) is colorful.6.What is the name of the wizard in "Harry Potter"?A. GandalfB. DumbledoreC. MerlinD. Harry PotterD7. A ____(delta) forms at the mouth of a river where it meets the sea.8.What is the main source of energy for the Earth?A. MoonB. SunC. StarsD. Wind9.What is the temperature at which water boils?A. 90 degrees CelsiusB. 100 degrees CelsiusC. 110 degrees CelsiusD. 120 degrees CelsiusB10.Napoleon Bonaparte was a leader from ________.11.We visit the ______ (博物馆) for educational purposes.12.What do you call a place where animals are kept for public viewing?A. ZooB. FarmC. AquariumD. CircusA13.What do we call the distance around a circle?A. DiameterB. RadiusC. CircumferenceD. Area14. A __________ (化学职业) offers diverse opportunities in various fields.15.The ________ is a small animal that loves to burrow.16.What do we call the term for the force that opposes motion?A. FrictionB. GravityC. InertiaD. MomentumA Friction17.What do we call a piece of land surrounded by water on all sides?A. PeninsulaB. IslandC. CoastD. BayB Island18.The _____ (果实) develops after a flower blooms.19.What is the term for a group of fish?A. SchoolB. PackC. FlockD. ColonyA20.The ______ helps fish to swim.21.The main purpose of a battery is to produce ______.22.The _______ (The Progressive Era) sought social and political reform.23.My __________ (玩具名) is the best __________ (名词) in the world!24.Chemical bonds can be ionic or ______.25.What do we call the sweet substance made by bees?A. SugarB. SyrupC. HoneyD. Jam26.We have music class on ___. (Thursday)27.What do we call the study of the weather?A. MeteorologyB. GeologyC. AstronomyD. BiologyA28.What is the opposite of quiet?A. LoudB. SoftC. CalmD. PeacefulA29.s were known for their advanced _______. (天文学) The Maya30.In a chemical reaction, the products may have different properties from the _____.31.I enjoy ______ with my family during vacations. (traveling)32.My favorite season is _______ (季节). I love the _______ (天气) and the _______ (活动) you can do.33.We have ______ (很多) fun at the playground.34.What is the capital of Iran?A. TehranB. BaghdadC. KabulD. DamascusA35.My favorite sport is ______ (篮球) because it is exciting and keeps me ______ (活跃).36.Energy from the sun is called ______ energy.37.What is the capital of Haiti?A. Port-au-PrinceB. Cap-HaïtienC. JacmelD. Les CayesA38.Which of these is a type of weather?A. SunnyB. LoudC. FastD. BrightA39.The chicken lays _______.40.The __________ is a major river in Russia. (伏尔加河)41.The _______ of a wave can be visualized with a sine curve.42.The ______ helps with the absorption of nutrients from food.43.I have a ______ of toys in my room. (collection)44.My friend is very __________ (有耐心的) with younger kids.45.The dog is ______ (barking) at the strangers.46.The ________ (种植计划) helps farmers.47. A buoyant object will float on ______.48.The city of Kathmandu is the capital of _______.49.What is the name of the famous scientist known for his laws of motion?A. Isaac NewtonB. Albert EinsteinC. Galileo GalileiD. Stephen Hawking50.How many legs does a typical insect have?A. 4B. 6C. 8D. 10B51.I like to help my mom ________ (打扫) the house.52.They are ___ (happy/sad) about the trip.53.The ______ (小鸡) can be yellow or brown.54.Which insect is known for making honey?A. AntB. BeeC. FlyD. Mosquito55.The __________ (历史的收藏) preserves our legacy.56.I enjoy spending time with my ______ during holidays.57.The __________ (历史的解释) evolves over time.58.The ________ (植物适应性) is impressive.59.What do we call the art of making films?A. FilmmakingB. DirectingC. ProducingD. Cinematography60. A rabbit can see almost ______ (所有方向).61.What is the primary color of a pumpkin?A. GreenB. OrangeC. YellowD. Brown62. A colloid is a mixture where tiny particles are ______ distributed.63.I learned how to ride a bike with my _________ (玩具车).64.I think it’s important to be curious and ask _______ (问题). It leads to new discoveries.65.The first known civilization was in __________ (美索不达米亚).66.My aunt loves __________ (旅游).67.What do we call the area of land that is covered by trees?A. ForestB. WoodlandC. JungleD. All of the aboveD All of the above68.When it rains, I like to wear my __________ coat. (防水的)69.We had ______ (fun) at the museum.70.The _______ is essential for healthy growth.71.My parents encourage me to donate some of my old ________ (玩具名) to children in need. I think it’s a ________ (形容词) idea!72.The ________ (rainbow) has many colors.73.The _____ (大象) is a gentle giant of the animal kingdom.74. A _______ can flourish in different environments.75.The __________ is a famous landmark in the United States. (自由女神像)76.What do you call the amount of space an object occupies?A. VolumeB. AreaC. MassD. Weight77.What is the main ingredient in salad?A. MeatB. VegetablesC. BreadD. Cheese78.Which insect produces honey?A. AntB. BeeC. FlyD. ButterflyB79.Which word means the opposite of "fast"?A. QuickB. SlowC. SpeedyD. RapidB80.What is the name of the famous American actress known for "The Princess Diaries"?A. Anne HathawayB. Mandy MooreC. Lindsay LohanD. Kristen StewartA81. A puma is also known as a ______ (美洲狮).82. A mixture that contains two or more phases is called a ______.83.I _____ (love/hate) to swim in the pool.84.corporate responsibility) promotes ethical business practices. The ____85.What do you call a young gopher?A. KitB. PupC. CalfD. Cub86.Matter can exist in three states: solid, ______, and gas.87.Which of these is a common pet?A. LionB. DogC. BearD. FoxB88. A ___ (小兔) has long ears and a fluffy tail.89.My favorite _____ is a spinning wheel.90.What is the capital of the Cayman Islands?A. George TownB. West BayC. Bodden TownD. North SideA91.What is the opposite of "happy"?A. SadB. ExcitedC. AngryD. Joyful92.What do you call the process of growing plants without soil?A. HydroponicsB. AeroponicsC. AquaponicsD. All of the aboveD93.What sound does a cow make?A. BarkB. MeowC. MooD. RoarC94.Sea is a ________ (盐水湖). The Dead95.What is the name of the famous American singer known for "Ain't No Mountain High Enough"?A. Diana RossB. Aretha FranklinC. Whitney HoustonD. Tina TurnerA96.The __________ is a major body of water in the Mediterranean. (地中海)97.I feel excited when I go to ________.98.My brother is my silly _______ who always knows how to make me laugh.99.My friend is very __________ (机智).100.The act of breaking a bond in a chemical reaction requires _______.。
小学下册英语第3单元真题(含答案)考试时间:80分钟(总分:110)B卷一、综合题(共计100题共100分)1. 填空题:I love to explore ________ (山谷) while hiking.2. 听力题:My dad _____ a bike to work. (rides)3. 选择题:What is the capital of Cuba?A. HavanaB. SantiagoC. CamagüeyD. Santa Clara答案:A4. 选择题:What is the name of the famous scientist known for his work on gravity?A. Albert EinsteinB. Isaac NewtonC. Nikola TeslaD. Thomas Edison答案: B5. 选择题:What is the name of the holiday celebrated on December 25?A. ThanksgivingB. EasterC. ChristmasD. Halloween答案:C6. 选择题:What do you call a person who writes poems?A. AuthorB. PoetC. NovelistD. Lyricist答案:B7. 选择题:What do we call the time it takes for the Earth to go around the sun?A. DayB. MonthC. YearD. Week答案:C8. 听力题:I can ______ my name in cursive. (write)9. 选择题:What is the name of the famous theme park located in California?A. DisneylandB. Universal StudiosC. SeaWorldD. Legoland答案:A10. 选择题:Which food is made from milk?A. BreadB. CheeseC. RiceD. Pasta11. 听力题:The flowers are ___ in the garden. (blooming)12. 听力题:The ancient Mayans are known for their ________ calendar.13. 选择题:What is the name of the famous painting of a girl holding a pearl earring?A. The Girl with a Pearl EarringB. The Mona LisaC. The Birth of VenusD. The Starry Night14. 填空题:The flamingo stands on one _______ (腿).We play _____ (乒乓球) after school.16. 填空题:The ancient Greeks wrote _______ about their gods. (史诗)17. 选择题:根据短文内容,选出Tom和 Chen Jie 书包里的物品。
小学上册英语第4单元真题(含答案)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 ______ helps with the digestion of food in the intestines.2. A _______ can provide food for your family.3.What is the freezing point of water?A. 0 degrees CelsiusB. 100 degrees CelsiusC. 32 degrees FahrenheitD. Both A and C答案:D4.I see a _____ balloon in the sky. (red)5.What do you call the art of folding paper into shapes?A. DrawingB. PaintingC. OrigamiD. Sculpture答案:C6.I like to ___ with my family. (spend time)7.The ______ (小鳄鱼) lives in swamps.8.The ______ is a talented actor.9.The capital of India is __________.10.My ________ (玩具) is a source of inspiration and joy.11.I love to visit my ________ (亲戚).12.The abolition of slavery was achieved in the ________ (19世纪).13. A _______ is a large area of land that is mostly flat.14. A __________ is a cold-blooded vertebrate.15.My friend is a _____ (演员) on a popular show.16.I have a red ______ (气球) for my birthday party. It floats high in the ______ (天空).17.What is the first letter of the alphabet?A. AB. BC. CD. D答案: A18.Chemical reactions often require an ______.19.The color change in a chemical reaction can indicate a ______.20. A goat climbs _______ (陡峭) mountains.21.I like to listen to ______ (music).22.My favorite flower is a ________.23.The _____ (运动场) is full of athletes.24.The chemical formula for calcium chloride is __________.25.The butterfly is ___ (fluttering) by.26.The ________ (magnifying glass) helps me see.27. A ____(public forum) invites community input.28.What is the chemical formula for table salt?A. NaClB. H2OC. CO2D. O2答案:A.NaCl29.What is the capital of Luxembourg?A. Luxembourg CityB. BrusselsC. AmsterdamD. Geneva答案:A. Luxembourg City30.The ancient Greeks held games every four years in ________.31. A chemical equation must be balanced to show the conservation of ______.32.My sister has a beautiful ______ (手链). She wears it every ______ (天).33.My mom is a great __________ (倡导者).34.The frog catches flies with its long ______ (舌头).35.The __________ can be used to classify different types of rocks.36.The fish is swimming ________ the water.37.I like to collect ______ (漫画书) featuring my favorite superheroes.38.Chemical changes can be identified by changes in ________ or color.39.What do you call a collection of stories?A. AnthologyB. NovelC. CompilationD. Collection答案:A40.The first printing press was invented by _______. (古腾堡)41.I love to visit ______ (科技中心) to see the latest innovations. It’s fascinating to learn about advancements.42.What is the name of the famous monument in India?A. Taj MahalB. Qutub MinarC. Gateway of IndiaD. Red Fort答案:A43.The __________ is a popular destination for families.44.The deer is graceful and _______ (优雅).45.My sister loves __________ (学习历史).46.The first human-made object to land on the moon was _______.47.My cousin is a great ____ (chef).48.The ancient Egyptians had a complex system of ________ (信仰).49.Gases have a ______ density compared to solids and liquids.50.What do you call the time of day when the sun rises?A. NightB. MorningC. AfternoonD. Evening答案: B51.On rainy days, I like to ______ (动词) with it indoors. It always makes me feel______ (形容词).52.The __________ is a region known for its innovative solutions.53.My cousin is a ______. She loves to create websites.54.The water is ________ in the lake.55.My grandmother makes __________ for us. (点心)nd use planning) balances development and conservation. The ____57.Metals are usually _____ (conductors) of electricity.58.The process of changing a liquid into a gas is called __________.59.The __________ (古代帝国) often expanded through conquest.60.When it’s hot, I l ike to stay in the __________. (阴凉处)61.The ________ (农业生产力) affects food supply.62.My sister has a passion for __________ (环保).63.I can play sports with my toy ________ (玩具名称).64. A ____(regional planning) coordinates development across areas.65.He is a _____ (工程师) who designs software.66. A _______ reaction occurs when a single compound breaks down into simpler substances.67.The ________ (国家公园管理) preserves nature.68. A rabbit has powerful ______ (后腿) for hopping.69.An object at rest stays at rest unless acted on by a _______.70.The dog is ___ (chasing) its tail.71.My friend gave me a ________ (玩具名称) for my birthday.72.The __________ (历史的交汇) creates new possibilities.73.My toy ______ is a bright yellow duck.74.I love to ______ (探索) new hobbies.75.The chemical symbol for tungsten is ______.76.I want to _____ (eat) ice cream.77.I enjoy my time with my ____.78.She has ___ (ten) fingers.79.The __________ is a region known for its rich soil.80.The chemical formula for lithium bromide is _______.81.The chemical symbol for iron is ______.82.The capital of Qatar is __________.83. A reaction that occurs spontaneously is called a ______ reaction.84.I admire people who follow their passions. They inspire me to pursue my own interests and dreams. I hope to find my passion in __________.85.The ______ teaches us about literature.86. A __________ can create new landforms over time.87.I have a toy _______ that can roll and spin.88.The study of ancient climates is called ______.89.I love to _____ (dance/sing) at school.90._____ (绿化) helps improve air quality.91.Certain plants are ______ (抗逆性强) and thrive in harsh conditions.92.The __________ is a region known for its biodiversity.93.What instrument is used to measure angles?A. RulerB. CompassC. ProtractorD. Caliper答案:C94.I often ask my __________ for help. (父母)95.What do we call the small pieces of food given to birds?A. SeedsB. CrumbsC. GrainsD. Pellets答案: A. Seeds96.What do we call the time it takes for the Earth to rotate once?A. YearB. MonthC. DayD. Hour答案:C97.The chemical symbol for iodine is ______.98.She is a wonderful _____ (老师).99.I saw a ________ chasing a squirrel.100. A chemical reaction can be represented by a _____ equation.。
...........................................................................................................................Assisted hatching of human embryos:asystematic review and meta-analysisof randomized controlled trialsWellington P.Martins 1,2,3,*,Isa A.Rocha 1,Rui A.Ferriani 1,3,and Carolina O.Nastri 1,21Departamento de Ginecologia e Obstetrı´cia da Faculdade de Medicina de Ribeira ˜o Preto da,Universidade de Sa ˜o Paulo (DGO FMRP-USP),Av.dos Bandeirantes,3900,Monte Alegre,8andar,Ribeira ˜o Preto,SP 14049-900,Brasil,CEP 2Escola de Ultra-sonografia e ReciclagemMe ´dica de Ribeira ˜o Preto (EURP),Ribeira ˜o Preto,SP,Brasil 3Instituto Nacional de Cie ˆncia e Tecnologia de Hormo ˆnios e Sau ´de da Mulher,Ribeira ˜o Preto,SP,BrasilCorrespondence address.Tel:+16-3602-2818;Fax:+16-3633-0946;E-mail:wpmartins@Submitted on September 20,2010;resubmitted on February 12,2011;accepted on March 9,2011table of contents†Introduction†Methods†Results†Discussionbackground:Assisted hatching (AH)is a manipulation of zona pellucida aiming to facilitate embryo implantation.methods:Systematic review and meta-analysis of medical literature was used to evaluate the effect of AH on assisted reproduction out-comes:clinical pregnancy,live birth,multiple pregnancy and miscarriage.Additional analysis was performed in these subgroups:(i)freshembryos transferred to unselected or non-poor prognosis women;(ii)fresh embryos transferred to women with previous repeatedfailure;(iii)fresh embryos transferred to women of advanced age;(iv)frozen-thawed embryos transferred to unselected or non-poor prog-nosis women.Analyses were based on risk ratio and 95%confidence intervals (RR,95%CIs)using Mantel–Haenszel random effects model.results:There were 28studies (5507participants)included.AH was related to a trend toward increased clinical pregnancy for all par-ticipants (RR ¼1.11,95%CI ¼1.00–1.24),with a significant increase in subgroups 2(RR ¼1.73;95%CI ¼1.37–2.17)and 4(RR ¼1.36;95%CI ¼1.08–1.72,P ,0.01),but not for subgroups 1and 3.For multiple pregnancy,a significant increase was observed for all partici-pants (RR ¼1.45;95%CI ¼1.11–1.90)and for subgroups 2(RR ¼2.53;95%CI ¼1.23–5.21)and 4(RR ¼3.40;95%CI ¼1.93–6.01).No significant heterogeneity was observed in subgroup analysis.conclusions:AH was related to increased clinical pregnancy and multiple pregnancy rates in women with previous repeated failure orfrozen-thawed embryos.However,AH is unlikely to increase clinical pregnancy rates when performed in fresh embryos transferred to unse-lected or non-poor prognosis women or to women of advanced age.Due to the small sample evaluated by the pool of included studies,noproper conclusions could be drawn regarding miscarriage or live birth.Key words:reproductive techniques /zona pellucida /embryo transfer /assisted hatchingIntroduction The embryo implantation rate in assisted reproduction procedures is 20%,which leads to a low clinical pregnancy rate, 35%,and even lower live birth rate, 25%,per cycle started (Gunby et al.,2010).Improving these rates is one of the main objectives of the new assistedreproduction technologies (ARTs).One of the most commonmethods to obtain better results is to obtain and to transfer multipleembryos,while freezing the spare embryos that can be used in futurecycles (Jungheim et al.,2009).However,this approach is associated&The Author 2011.Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.All rights reserved.For Permissions,please email:journals.permissions@ Human Reproduction Update,Vol.17,No.4pp.438–453,2011Advanced Access publication on April 7,2011doi:10.1093/humupd/dmr012by guest on August 8, 2012/Downloaded fromwith the two main problems of ARTs:multiple pregnancy (Bissonnette et al.,2007)and ovarian hyperstimulation syndrome (Nastri et al.,2010).Low embryo quality and poor endometrial receptivity are fre-quently denoted as the main reasons for the low implantation rate in humans.Additionally,some researchers believe that difficulties during the blastocyst hatching process could also negatively interfere with the implantation process (Cohen et al.,1990).The human embryo is surrounded by a glycoprotein layer,named as the zona pellucida,which permits only acrosome-intact sperm to fer-tilize the oocyte and blocks the entry of multiple sperm.After fertiliza-tion,the zona pellucida compresses and shapes the embryo,facilitating the passage through the Fallopian tubes into the endometrial cavity and protects the embryo from micro-organisms and immune cells(Zhao and Dean,2002).The embryo at the blastocyst stage then breaks out of this protective layer to start the deployment process,and failure at this stage can prevent implantation.The artificial rupture of the zona pellucida is known as assisted hatching (AH)and this technique has been used since the late 1980s (Cohen et al.,1988),in attempts to improve the chances of implantation and clinical pregnancy during assisted reproduction.There are three possible mechanisms by which AH could improve embryo implantation.(i)Zona pellucida hardening caused by IVF and cell culture (DeMeestere et al.,1997)or cryopreservation (Carroll et al.,1990)might make hatching difficult,which could be solved by AH.(ii)AH is associated with the anticipation of implantation in humans (Liu et al.,1993),which is particularly relevant since the implantation window seems to occur 1–2days earlier in womenundergoing ovarian stimulation with exogenous gonadotrophins when compared with women during their natural cycles (Nikaset al.,1999).(iii)Artificial opening could also serve as a channel for exchange of metabolites,growth factors and messages between the embryo and endometrium (Cohen et al.,1992b ).However,there is currently no recommendation to perform AH routinely in women undergoing assisted reproduction (ASRM,2008),since no singlestudy has been able to demonstrate sufficient evidence favorable to AH.However,no study has included a sufficient sample to properly evaluate the effect of AH on assisted reproduction outcomes;this sample could be easily obtained by a meta-analysis.Methods Eligibility criteria Eligibility was confined to randomized controlled trials published as fullarticles evaluating the effect of AH human embryos compared with a control group in which embryos were not submitted to AH.Additionally,in order to reduce heterogeneity,analyses were also performed in these subgroups:(i)fresh embryos transferred to unselected or non-poor prog-nosis women;(ii)fresh embryos transferred to women with previous repeated failure;(iii)fresh embryos transferred to women of advanced age;and (iv)frozen/thawed embryos transferred to unselected or non-poor prognosis women.By non-poor prognosis women,we are refer-ring to women evaluated by studies that used as inclusion criteria at least one of the following:a maximum age;a maximum FSH value;a maximumnumber of previous unsuccessful IVF attempts;a minimum number of embryos available to be transferred;the absence of uterine abnormalities.The subgroup analysis was performed because there is a doubt about whether AH may be beneficial for every woman undergoing ARTs,regardless of any specific condition;this issue is assessed by subgroup 1analysis.The clustering of women into the three other subgroups (pre-vious repeated failure,advanced maternal age and frozen/thawedembryos)was based on the specific situations most investigated byRCTs,since a greater/better effect of AH is expected (ASRM,2008;Ge et al.,2008).However,the underlying mechanisms by which womenwould benefit from AH are different for each subgroup.In subgroup 2,we are considering that repeated unsuccessful attempts may be relatedto difficulties in the hatching process;in subgroup 3,we are investigatingthe hypothesis that maternal age has a negative impact on the embryonic hatching;and in subgroup 4,we are taking into account the possibility thatthe process of freezing/thawing could hinder embryo hatching,likely byincreasing the rigidity of the zona pellucida.Information sourcesStudies were identified by searching electronic databases and scanningreference lists of articles by two independent reviewers (W.P.M.andI.A.R.).The search was last performed on 1December 2010.The elec-tronic searches were performed using both PubMed and OvidSP andincluded the following databases:MEDLINE,Cochrane Central Registerof Controlled Trials and Cochrane Database of Systematic Reviews,Cochrane Methodology Register,Database of Abstracts of Reviews ofEffects and Biological Abstracts.The following terms were used in elec-tronic search:[(zona pellucida)or (AH)]and [(implantation)or (preg-nancy)].We did not search for ongoing trials.Eligibility assessment wasperformed independently in a non-blinded standardized manner by tworeviewers (W.P.M.and I.A.R.).Disagreements between reviewers were resolved by consensus.Data collection processData were collected in a sheet based on the Cochrane Consumers andCommunication Review Group’s data extraction template.One reviewauthor (W.P.M.)extracted the following data from included studies andthe second author (I.A.R.)checked the extracted data.Disagreementswere resolved by discussion between the authors.Data itemsThe following data were extracted from included studies:(i)methods:aimof intervention,method of recruitment of participants,inclusion/exclusioncriteria,and if informed consent was obtained as well as ethical approval;(ii)participants characteristics:number and age;(iii)intervention:methodused for AH and time of AH;and (iv)results:number of women,clinicalpregnancy,live birth,multiple pregnancy and miscarriage.Data regardingrandomization,allocation concealment,blinding and other sources ofbias were evaluated in the included studies.Summary measuresAll results were combined for meta-analysis with Review Manager 5forWindows (Copenhagen:The Nordic Cochrane Centre,The CochraneCollaboration,2008).The meta-analysis was performed using Mantel–Haenszel random effects model.The number of women who were ran-domly allocated was considered as the total number of participants.Riskratios (RR),95%confidence intervals (95%CIs),and P -values were calcu-lated.To evaluate the power,we arbitrarily defined as clinically relevant aRR ≥1.2(a relative increase ≥20%in the evaluated outcome).Analysis of heterogeneityHeterogeneity between studies was assessed using t 2,x 2and I 2.Currently,I 2is the preferred test to evaluate inconsistency across studies,as thisdescribes the percentage of the variability in effect estimates that is due Assisted hatching 439by guest on August 8, 2012/Downloaded fromto heterogeneity rather than sampling error (chance)(Higgins and Green,2009).For interpretation of I 2:0–40%:might not be important;30–60%:may represent moderate heterogeneity;50–90%:may represent substan-tial heterogeneity and 75–100%may indicate considerable heterogeneity.Results Study selection The electronic search retrieved a total of 1160citations (1528before adjusting for duplicates).After reading titles and abstracts,1105studies were discarded because the articles clearly did not meet the criteria due to one of the following aspects:the study (i)did not evalu-ate the effect of AH performed in human embryos during assisted reproduction (n ¼997);(ii)was not a randomized controlled trial (n ¼95)or (iii)did not have a control group where AH was not per-formed (n ¼13).From the 55fully evaluated articles,27were excluded with reasons:18studies were not randomized or were pseudo-randomized (Tucker et al.,1991;Obruca et al.,1994a ,b ;Takahashi et al.,1994;Anti-nori et al.,1996a ;Bider et al.,1997;Tao and Tamis,1997;Edirisinghe et al.,1999;Hershlag et al.,1999;Mansour et al.,2000;Horng et al.,2002;Kinget et al.,2002;Gabrielsen et al.,2004;Frydman et al.,2006;Yano et al.,2007;Valojerdi et al.,2008;Debrock et al.,2009;Zhang et al.,2009);four studies were excluded because they did not provide per woman data (Magli et al.,1998;Nakayama et al.,1999;Ebner et al.,2002;Ma et al.,2006);two studies did not provide any of the evaluated outcomes (Liu et al .,1993;Wong et al.,2003);in one study,women who were submitted to AH also used either placebo or methylprednisolone +doxycycline (Primi et al.,2004),while women in the control group were not submitted to neither placebo nor methylprednisolone +doxycycline;in one study,the control group consisted of women whose embryos were submitted to selective AH (Cohen et al.,1992a );and one study had conflicting results (Tucker et al.,1996):in the group of AH the authors reported 21clinical preg-nancies but they also stated that only 16embryo implantations were observed.Therefore,28studies were included in this meta-analysis and theflowchart of study selection is shown in Fig.1.We created two sec-tions in three studies (Petersen et al.,2005;Ge et al .,2008;Kutluet al.,2010)and three sections in one study (Cohen et al .,1992b ),since completely different trials evaluating women and/or embryoswith different characteristics were reported inside these studies.Con-sidering these divisions,33trials were evaluated.Characteristics of included studiesThe characteristics of the included studies are described in Table I .Regarding subgroup analysis,12trials were included in the subgroup‘fresh embryos transferred to unselected or non-poor prognosiswomen’;five trials were included in the subgroup ‘fresh embryostransferred to women with previous repeated failure’;four trialswere in the subgroup ‘fresh embryos transferred to women withadvanced age’and six trials were in the subgroup ‘frozen-thawedembryos transferred to unselected or non-poor prognosis women’(Table I ).Additionally,we evaluated more than six trials from fivestudies which did not fit in any of the previously described subgroups(Table I ).The first trial from the study by Cohen et al .(1992b)wasincluded in the subgroup fresh embryos transferred to unselected ornon-poor prognosis women;however,the second trial comparedthe selective AH (AH performed only in poor prognosis embryos)with a control group,both from woman with Day 3FSH ≤15IU/l,and the third trial evaluated AH performed in all fresh embryosfrom women with Day 3FSH .15IU/l.The study of Hagemannet al .(2010)included only women whose embryos had a zona pellu-cida thickness of ≥13m m,and AH was only performed on theseembryos.The study of Nadir Ciray et al .(2005)included onlywomen with endometriosis.The study of Rufas-Sapir et al .(2004)included only women with repeated previous failure (≥3)who hadat least 3–4grade A or B embryos.The study from Valojerdi et al .(2010)included only women submitted to vitrified–warmed embryotransfer.Regarding the subgroup ‘frozen-thawed embryos transferred tounselected or non-poor prognosis women’,one may still consider achance of bias by selecting other specific subgroups of womenfor Figure 1Flowchart of study selection.440Martins et al .by guest on August 8, 2012/Downloaded fromthe transfer of frozen embryos (e.g.advanced age and/or previous repeated failure).However,all RCTs evaluating frozen/thawed embryos included only unselected or non-prognosis women:the authors from these studies likely did not evaluate two or more specific conditions at a same time to avoid confusion when interpreting the results.Clinical pregnancy There were 33trials from 28studies (5507participants)that reported clinical pregnancy as an outcome and were included (Fig.2).We observed a trend toward increased clinical pregnancy considering the pooled data analysis (RR ¼1.11;95%CI ¼1.00–1.24;P ¼0.05);however,the observed increase was lower than we arbitrarily defined as clinically relevant (RR ≥1.2)and there was substantial het-erogeneity between studies (I 2¼49%).Considering single study data,only four trials reported a significant increase in clinical pregnancy rate (Fig.2):two evaluating AH in fresh embryos transferred to women with previous repeated failure,one using laser (Antinori et al.,1996b ),and the other using acid Tyrode ´s (Jelinkova et al.,2003);and two evaluating AH in frozen-thawed embryos transferred to unse-lected or non-poor prognosis women,one using laser (Balaban et al.,2006)and the other using mechanical expansion (Fang et al.,2010).However,there was one study demonstrating a significant decrease in clinical pregnancy rate when AH was performed in vitrified–warmed embryos using laser (Valojerdi et al .,2010).When evaluating the subgroup ‘fresh embryos transferred to unse-lected or non-poor prognosis women’,12trials (2140participants)were included (Fig.2).AH was not associated with significant changes in clinical pregnancy in any of them and the same was observed in the meta-analysis (RR ¼1.05;95%CI ¼0.95–1.15).No significant heterogeneity was observed (I 2¼0%),although the method used for performing AH was different between trials (laser ¼6,acid Tyrode ´s ¼3and pronase ¼2,mechanical ¼1).Con-sidering the observed clinical pregnancy rate in the control group (447/1031¼43.4%),the power to detect a RR ≥1.2was very high (97.6%).Considering the subgroup ‘fresh embryos transferred to women with repeated previous failure ’,five trials (761participants)were included (Fig.2).AH was associated with a significant increase in clini-cal pregnancy rate in two of them and the same was observed as the result of our meta-analysis (RR ¼1.73;95%CI ¼1.37–2.17).We considered the increase in clinical pregnancy rate as clinically relevant (RR .1.2).No significant heterogeneity was observed (I 2¼0%),although the method used for performing AH was different between trials (laser ¼2,acid Tyrode ´s ¼2and pronase ¼1).Regarding the subgroup ‘fresh embryos transferred to women with advanced age ’,four trials (405participants)were included (Fig.2).No significant heterogeneity was observed (I 2¼0%)although different methods of AH were used (laser ¼3and acid Tyrode ´s ¼1).AH was not associated with significant changes in clinical pregnancy rate in any of these four trials and the same was observed in the meta-analysis (RR ¼0.96;95%CI ¼0.74–1.25).Considering the observed clinical pregnancy rate in the control group (73/207¼41.8%),the power to detect a RR ≥1.2was low (46.8%).However,we believe that AH is unlikely to relevantly improve clinical pregnancy in women with advanced age,since the observed clinical pregnancy was lower (although not significantly)when AH was performed (33.3versus 35.3%;AH versus control,respectively;P ¼0.77).In the subgroup ‘Frozen-thawed embryos transferred to unselected or non-poor prognosis women’(Fig.2),six trials (1196participants)were included.AH was associated with a significant increase in clinicalpregnancy rate in two of them and in the meta-analysis (RR ¼1.36;95%CI ¼1.08–1.72).The observed heterogeneity (I 2¼14%)was not important,albeit the method used to perform AH was differ-ent between studies (laser ¼4,mechanical expansion ¼1and pronase ¼1).In the six trials evaluating AH performed in other situations (1005participants—Fig.2),the pooled data analysis did not demonstrate any significant difference in clinical pregnancy rate,although data from one trial demonstrated a significant decrease.A substantial het-erogeneity I 2¼67%was observed between the results of these trials evaluating AH performed in different situations and using different methods (acid Tyrode ´s ¼4and laser ¼2).Live birth/ongoing pregnancyThere were 16trials from 14studies (2562participants)which reported live birth or ongoing pregnancy as an outcome and were included (Fig.3).No significant change in live birth rate was observed considering results from single trials or the meta-analysis (RR ¼1.03;95%CI ¼0.91–1.16).No significant heterogeneity was observed (I 2¼0%),although these trials evaluated AH performed in different situations and using different methods.Considering the observed live birth rate in the control group (337/1266¼26.6%),the power to detect an RR ≥1.2was 82.7%.In subgroup analysis,the only signifi-cant difference was observed in women with previous repeated failure:the pooled analysis from two studies (250participants,Fig.3)demon-strate an increased live birth rate (RR ¼2.51;95%CI ¼1.06–5.96).In the other subgroups,no significant differences were observed;however,the power to demonstrate a 20%relative increase in live birth rate was low.Multiple pregnancyThere were 17trials from 15studies (3551participants)that reported on multiple pregnancy and were included (Fig.4).A significant increase in multiple pregnancy rate was observed considering the pooled data analysis (RR ¼1.45;95%CI ¼1.11–1.90).The increase in multiple pregnancy was higher (although with a small overlap in 95%CI)than that observed for clinical pregnancy rate (RR ¼1.11;95%CI ¼1.00–1.24).The heterogeneity observed between studies may be considered as low to moderate (I 2¼41%).Considering single study data,only two trials reported a significant increase in multiple preg-nancy rate:one evaluating AH using acid Tyrode ´s in fresh embryos transferred to women with previous repeated failure (Jelinkova et al .,2003);and the other evaluating AH using laser in frozen-thawed embryos transferred to unselected or non-poor prognosis women (Balaban et al .,2006).When evaluating the subgroup ‘fresh embryos transferred to unselected or non-poor prognosis women’,eight trials (1610partici-pants)were included (Fig.4).AH was not associated with significant changes in multiple pregnancy rate in any of them,but a trend of increase was observed in the meta-analysis (RR ¼1.20;95%446Martins et al . by guest on August 8, 2012/Downloaded fromCI ¼0.97–1.48).Considering the observed multiple pregnancy rate in the control group (123/770¼16.0%),the power to detect a RR ≥1.2was only 34.6%.No significant heterogeneity was observed (I 2¼0%),although the method used for performing AH was different between trials (laser ¼3,acid Tyrode ´s ¼2,pronase ¼2and mechanical ¼1).Figure 2Effect of AH on clinical pregnancy.Assisted hatching 447 by guest on August 8, 2012/Downloaded fromThree trials (527participants)were included in the subgroup ‘fresh embryos transferred to women with repeated previous failure ’(Fig.4).AH was associated with a significant increase in multiple pregnancy rate in one of them (Jelinkova et al .,2003)and the same was observed as the result of our meta-analysis (RR ¼2.53;95%CI ¼1.23–5.21).No significant heterogeneity was observed (I 2¼0%),although the method used for performing AH was different between trials (laser ¼1,acid Tyrode ´s ¼1and mechanical ¼1).No trial reported this outcome in the subgroup ‘fresh embryos transferred to women with advanced age ’(Fig.4).Four trials (851participants)were included in the subgroup ‘Frozen-thawed embryos transferred to unselected or non-poor prog-nosis women’(Fig.4).AH was associated with a significant increase in multiple pregnancy rate in one trial (Balaban et al .,2006)and in the meta-analysis (RR ¼3.40;95%CI ¼1.93–6.01).No significant het-erogeneity was observed (I 2¼0%),although the method used for performing AH was different between trials (laser ¼3and pronase ¼1).In the two trials evaluating AH performed in other situations (Fig.4),there was considerable heterogeneity (I 2¼83%).One of these trials observed a trend of increased multiple pregnancy (RR ¼1.59;95%CI ¼0.90–2.82)when AH using acid Tyrode ´s was per-formed on poor prognosis embryos from non-poor prognosis women (Cohen et al .,1992b ).In the other trial,a trend of decreased multiple pregnancy was observed (RR ¼0.52;95%CI ¼0.26–1.06)when AH by laser was performed on vitrified–warmed embryos (Valojerdi et al .,2010).Figure 3Effect of AH on live birth/ongoing pregnancy.by guest on August 8, 2012/Downloaded fromMiscarriage There were 17trials from 16studies (2398participants)that reported on miscarriage and were included (Fig.5).No significant heterogeneity was observed between the studies (I 2¼0%).No significant change in the risk of miscarriage was observed considering the result from any single trial or the pooled data analysis (RR ¼1.02;95%CI ¼0.72–1.45).However,considering the observed miscarriage rate in the control group (56/1191¼4.7%),the power to detect an RR ≥1.2was only 17.4%.Discussion AH was associated with a trend toward increased clinical pregnancy when considering pooled data from all studies (RR ¼1.11;95%CI ¼1.00–1.24,P ¼0.05).However,a substantial heterogeneity was observed (I 2¼49%)and therefore this result should not be extrapolated for every situation.Moreover,the observed increment was small (only an 11%relative increase)and may not be considered important enough to justify the increment in costs and risks associated with AH.In subgroup evaluation,AH was associated with a significant and clinically relevant improvement in clinical pregnancy rate when performed in fresh embryos transferred to women with repeated pre-vious failure (RR ¼1.73;95%CI ¼1.37–2.17)or in frozen-thawedembryos transferred to unselected or non-poor prognosis women(RR ¼1.36;95%CI ¼1.08–1.72).Contrarily,AH was not associatedwith any increment in pregnancy rate when performed in fresh embryos transferred to unselected or non-poor prognosiswomen.Figure 4Effect of AH on multiple pregnancy.by guest on August 8, 2012/Downloaded fromMoreover,a slight (but not significant)decrease in clinical pregnancy was observed when combining the results from the four trials evaluat-ing women with advanced age.No significant heterogeneity was observed in any subgroup analysis,despite the fact that AH was per-formed by different methods.Regarding multiple pregnancy,the observed results were not very different from those observed for clinical pregnancy.AH was associ-ated with a significant and clinically relevant increase in clinical multiple pregnancy rate considering pooled data from all studies (RR ¼1.45;95%CI ¼1.11–1.90),but a moderate heterogeneity was observed (I 2¼41%).In subgroup evaluation,AH was associated with a signifi-cant and clinically relevant improvement in clinical multiple pregnancy when performed in fresh embryos transferred to women with repeated previous failure (RR ¼2.53;95%CI ¼1.23–5.21)or in frozen-thawed embryos transferred to unselected or non-poor prog-nosis women (RR ¼3.40;95%CI ¼1.93–6.01).A trend toward increased multiple pregnancy was observed in fresh embryos trans-ferred to unselected or non-poor prognosis women (RR ¼1.20;95%CI ¼0.97–1.48).Similarly,no significant heterogeneity was observed in subgroup analysis,despite different methods used to perform AH.Due to the small sample evaluated by the pool of included studies,no proper conclusions could be drawn regarding live birth or miscar-riage.This is the main weakness of this meta-analysis:thesetwo Figure 5Effect of AH on miscarriage.by guest on August 8, 2012/Downloaded from。