Silberschatz, Galvin and Gagne ?2002
10.1Operating System Concepts Chapter 10: Virtual Memory
n Background
n Demand Paging
n Process Creation
n Page Replacement
n Allocation of Frames
n Thrashing
n Operating System Examples Silberschatz, Galvin and Gagne ?2002
10.2Operating System Concepts Background
n Virtual memory –separation of user logical memory from physical memory.
F Only part of the program needs to be in memory for
execution.
F Logical address space can therefore be much larger than physical address space.
F Allows address spaces to be shared by several processes.F Allows for more efficient process creation.
n Virtual memory can be implemented via:
F Demand paging
F Demand segmentation
Silberschatz, Galvin and Gagne ?2002
10.3Operating System Concepts Virtual Memory That is Larger Than Physical Memory Silberschatz, Galvin and Gagne ?2002
10.4Operating System Concepts Demand Paging
n Bring a page into memory only when it is needed.
F Less I/O needed
F Less memory needed
F Faster response
F More users
n Page is needed ?reference to it
F invalid reference ?abort
F not-in-memory ?bring to memory
Silberschatz, Galvin and Gagne ?2002
10.5Operating System Concepts Transfer of a Paged Memory to Contiguous Disk Space Silberschatz, Galvin and Gagne ?2002
10.6Operating System Concepts Valid-Invalid Bit
n With each page table entry a valid–invalid bit is
associated
(1 ?in-memory, 0?not-in-memory)
n Initially valid–invalid but is set to 0 on all entries.
n Example of a page table snapshot.n During address translation, if valid–invalid bit in page
table entry is 0 ?page fault.
1
1
1
1
M
Frame #valid-invalid bit
page table
Silberschatz, Galvin and Gagne ?2002
10.7Operating System Concepts Page Table When Some Pages Are Not in Main Memory Silberschatz, Galvin and Gagne ?2002
10.8Operating System Concepts Page Fault
n If there is ever a reference to a page, first reference will
trap to
OS ?page fault
n OS looks at another table to decide:
F Invalid reference ?abort.
F Just not in memory.
n Get empty frame.
n Swap page into frame.
n Reset tables, validation bit = 1.
n Restart instruction: Least Recently Used
F block move
F auto increment/decrement location
Silberschatz, Galvin and Gagne ?2002
10.9Operating System Concepts Steps in Handling a Page Fault Silberschatz, Galvin and Gagne ?2002
10.10Operating System Concepts What happens if there is no free frame?
n Page replacement –find some page in memory, but not
really in use, swap it out.
F algorithm
F performance –want an algorithm which will result in
minimum number of page faults.
n Same page may be brought into memory several times.
Silberschatz, Galvin and Gagne ?2002
10.11Operating System Concepts Performance of Demand Paging n Page Fault Rate 0 ≤p ≤1.0
F if p = 0 no page faults
F if p = 1, every reference is a fault
n Effective Access Time (EAT)
EAT = (1 –p ) x memory access
+ p (page fault overhead
+ [swap page out ]
+ swap page in + restart overhead)
Silberschatz, Galvin and Gagne ?2002
10.12Operating System Concepts Demand Paging Example
n Memory access time = 1 microsecond
n 50% of the time the page that is being replaced has been modified and therefore needs to be swapped out.
n Swap Page Time = 10 msec = 10,000 msec
EAT = (1 –p) x 1 + p (15000)
1 + 15000P (in msec)
Silberschatz, Galvin and Gagne ?2002
10.13Operating System Concepts Process Creation
n Virtual memory allows other benefits during process creation:
-Copy-on-Write
-Memory-Mapped Files Silberschatz, Galvin and Gagne ?2002
10.14Operating System Concepts Copy-on-Write
n Copy-on-Write (COW) allows both parent and child processes to initially share the same pages in memory.If either process modifies a shared page, only then is the page copied.
n COW allows more efficient process creation as only modified pages are copied.
n Free pages are allocated from a pool of zeroed-out pages.
Silberschatz, Galvin and Gagne ?2002
10.15Operating System Concepts Memory-Mapped Files
n Memory-mapped file I/O allows file I/O to be treated as routine memory access by mapping a disk block to a page in memory.n A file is initially read using demand paging. A page-sized portion of the file is read from the file system into a physical page. Subsequent reads/writes to/from the file are treated as ordinary memory accesses.
n Simplifies file access by treating file I/O through memory rather than read()write()system calls.
n Also allows several processes to map the same file allowing the pages in memory to be shared.
Silberschatz, Galvin and Gagne ?2002
10.16Operating System Concepts Memory Mapped Files
Silberschatz, Galvin and Gagne ?2002
10.17Operating System Concepts Page Replacement
n Prevent over-allocation of memory by modifying page-fault service routine to include page replacement.
n Use modify (dirty ) bit to reduce overhead of page transfers –only modified pages are written to disk.
n Page replacement completes separation between logical memory and physical memory –large virtual memory can be provided on a smaller physical memory.
Silberschatz, Galvin and Gagne ?2002
10.18Operating System Concepts Need For Page Replacement
Silberschatz, Galvin and Gagne ?2002
10.19Operating System Concepts Basic Page Replacement
1.Find the location of the desired page on disk.
2.Find a free frame:
-If there is a free frame, use it.
-If there is no free frame, use a page replacement
algorithm to select a victim frame.
3.Read the desired page into the (newly) free frame. Update the page and frame tables.
4.Restart the process.
Silberschatz, Galvin and Gagne ?2002
10.20Operating System Concepts Page Replacement
Silberschatz, Galvin and Gagne ?2002
10.21Operating System Concepts Page Replacement Algorithms
n Want lowest page-fault rate.
n Evaluate algorithm by running it on a particular string of
memory references (reference string) and computing the
number of page faults on that string.
n In all our examples, the reference string is 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5.
Silberschatz, Galvin and Gagne ?2002
10.22Operating System Concepts Graph of Page Faults Versus The Number of Frames
Silberschatz, Galvin and Gagne ?2002
10.23Operating System Concepts First-In-First-Out (FIFO) Algorithm n Reference string: 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5
n 3 frames (3 pages can be in memory at a time per process)
n 4 frames n FIFO Replacement –Belady’s Anomaly
F more frames ?less page faults
1231234125
34
9 page faults
123123512
4
510 page faults
443
Silberschatz, Galvin and Gagne ?2002
10.24Operating System Concepts FIFO Page Replacement
Silberschatz, Galvin and Gagne ?2002
10.25Operating System Concepts FIFO Illustrating Belady’s Anamoly Silberschatz, Galvin and Gagne ?2002
10.26Operating System Concepts Optimal Algorithm
n Replace page that will not be used for longest period of time.
n 4 frames example
1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5
n How do you know this?
n Used for measuring how well your algorithm performs.123
4
6 page faults
45
Silberschatz, Galvin and Gagne ?2002
10.27Operating System Concepts Optimal Page Replacement Silberschatz, Galvin and Gagne ?2002
10.28Operating System Concepts Least Recently Used (LRU) Algorithm n Reference string: 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5
n Counter implementation
F Every page entry has a counter; every time page is
referenced through this entry, copy the clock into the
counter.
F When a page needs to be changed, look at the counters to determine which are to change.
12
35
4
43
5
Silberschatz, Galvin and Gagne ?2002
10.29Operating System Concepts LRU Page Replacement Silberschatz, Galvin and Gagne ?2002
10.30Operating System Concepts LRU Algorithm (Cont.)
n Stack implementation –keep a stack of page numbers in a double link form:
F Page referenced:
4move it to the top
4requires 6 pointers to be changed
F No search for replacement
Silberschatz, Galvin and Gagne ?2002
10.31Operating System Concepts Use Of A Stack to Record The Most Recent Page References Silberschatz, Galvin and Gagne ?2002
10.32Operating System Concepts LRU Approximation Algorithms
n Reference bit
F With each page associate a bit, initially = 0
F When page is referenced bit set to 1.
F Replace the one which is 0 (if one exists). We do not know
the order, however.
n Second chance
F Need reference bit.
F Clock replacement.
F If page to be replaced (in clock order) has reference bit = 1.
then:
4set reference bit 0.
4leave page in memory.
4replace next page (in clock order), subject to same
rules.
Silberschatz, Galvin and Gagne ?2002
10.33Operating System Concepts Second-Chance (clock) Page-Replacement Algorithm Silberschatz, Galvin and Gagne ?2002
10.34Operating System Concepts Counting Algorithms
n Keep a counter of the number of references that have
been made to each page.
n LFU Algorithm: replaces page with smallest count.
n MFU Algorithm: based on the argument that the page
with the smallest count was probably just brought in and
has yet to be used.
Silberschatz, Galvin and Gagne ?2002
10.35Operating System Concepts Allocation of Frames
n Each process needs minimum number of pages.n Example: IBM 370 –6 pages to handle SS MOVE instruction:
F instruction is 6 bytes, might span 2 pages.
F 2 pages to handle from .
F 2 pages to handle to .
n Two major allocation schemes.
F fixed allocation
F priority allocation Silberschatz, Galvin and Gagne ?2002
10.36Operating System Concepts Fixed Allocation
n Equal allocation –e.g., if 100 frames and 5 processes, give each 20 pages.
n Proportional allocation –Allocate according to the size of process.
m
S s
p a m s S p s i
i i i
i
i ×===∑== for allocation frames
of number total process of size 59
64137127
5
6413710
127
10
64
212≈×=≈×====a a s s m i
Silberschatz, Galvin and Gagne ?2002
10.37Operating System Concepts Priority Allocation
n Use a proportional allocation scheme using priorities rather than size.
n If process P i generates a page fault,
F select for replacement one of its frames.
F select for replacement a frame from a process with lower priority number.
Silberschatz, Galvin and Gagne ?2002
10.38Operating System Concepts Global vs. Local Allocation
n Global replacement –process selects a replacement frame from the set of all frames; one process can take a frame from another.
n Local replacement –each process selects from only its own set of allocated frames.
Silberschatz, Galvin and Gagne ?2002
10.39Operating System Concepts Thrashing
n If a process does not have “enough” pages, the page-fault rate is very high. This leads to:
F low CPU utilization.
F operating system thinks that it needs to increase the degree of multiprogramming.
F another process added to the system.
n Thrashing ≡a process is busy swapping pages in and out.
Silberschatz, Galvin and Gagne ?2002
10.40Operating System Concepts Thrashing
n Why does paging work?
Locality model
F Process migrates from one locality to another.
F Localities may overlap.
n Why does thrashing occur?
Σsize of locality > total memory size
教学目标： 1.让学生掌握英语学习中的五种基本句型； 2.学会分辨句子属于哪种句型； 3.懂得使用不同的句型造句； 教学重点与难点： 1.五种句型的分析与理解； 2.句型4（主+动+宾+补）与句型5（主+动+宾+宾）的掌握与比较； 教学方法： 1.ppt演示； 课堂练习： 一、下列的句子属于哪种类型 1. The sun rises 2. She is walking along the lake. 3. I like this book very much. 4. That man seems kind 5. He bought his sister a piano. 6. She kept us waiting for over three hours. 7. Let me give you a hand. 8. We tried to make her happy. 二、请说出五个句子，并说出属于哪种句型 家庭作业： 1.每个句型各举出3个句子 2.翻译句子
导入主题：我们现在能用英语写简单的作文，也可以用英语进行简单的交流与沟通，可是大家知道英语中有多少种基本句型吗？那这些句型分别是什么？ （让学生自由思考、讨论，引出今天的课题，英语学习中的五种基本句型）1.Subject (主语) ＋Verb (谓语) 此句型的特点是:谓语动词是不及物动词,本身能表达完整的意思,后面不需跟宾语,但有时可跟副词、介词短语等作状语。如: He laughed. John has read widely. He lives in London. 2. Subject(主语) ＋Verb (谓语) ＋Object (宾语) 此句型的特点是:谓语动词是及物动词,不能表达完整的意思,必须跟有一个宾语。如: Our team beat all the others. 3. Subject (主语) ＋Link. V(系动词) ＋Predicate(表语) 此句型的特点是:谓语动词是连系动词,不能表达完整的意思,必须加上一个表明主语特征、身份、状态的表语。常见的系动词有:be(是),become(成为),get(变得),turn(变得),grow(变得),look(看起来),feel(感到),smell(闻起来),taste(尝起来),sound(听起来),seem(似乎),keep(保持),stay(保持)等。如: The rose smells sweet. 4. Subject(主语)＋Verb (动词)＋Object (宾语)＋Complement(补语) 此句型的特点是:谓语动词虽然跟有一个宾语,但意思还不完整,必须加上另外一个成分(宾语补足语)对宾语进行补充说明。可以用作宾语补足语的有:名词、形容词、不定式、动名词、分词、介词短语等。如: We must keep our school clean. They made him their monitor. 5. Subject(主语)＋Verb(谓语)＋Indirect object(间接宾语)＋Direct object (直接宾语) 此句型的特点是:谓语动词跟有两个宾语,这两个宾语都是动作的对象或承受者,其中指人的是间接宾语,指物的是直接宾语。当间接宾语放在直接宾语之后时,通常需要加介词for或to。可跟双宾语的动词 有:answer,bring,buy,find,get,give,lend,make,pass,pay,send,show,sing,take,teach,tell, write等。如: Mr. Li told us an interesting story. Would you please give this dictionary to Li Hua？ 【注】S=Subject(主语). V=Verb(谓语动词). P=Predicative(表语). O=Object(宾语).
固定句型及固定搭配归纳 一、接不定式（而不接动名词）作宾语的常用动词（意思是此类动词后面要接动词时需用to do 形式，而不能用V.ing形式） afford to do sth. 负担得起做某事 agree to do sth. 同意做某事arrange to do sth.安排做某事ask to do sth. 要求做某事demand to do sth. 要求做某事choose to do sth. 决定做某事decide to do sth. 决定做某事determine to do sth. 决心做某expect to do sth. 期待做某事help to do sth. 帮助做某事wish to do sth. 希望做某事hope to do sth. 希望做某事learn to do sth. 学习做某事manage to do sth. 设法做某事offer to do sth. 主动提出做某plan to do sth. 计划做某事prepare to do sth. 准备做某事pretend to do sth. 假装做某事promise to do sth. 答应做某事refuse to do sth. 拒绝做某事want to do sth. 想要做某事 注：有些不及物动词后习惯上也接不定式，不接动名词： fail to do sth. 未能做某事long to do sth. 渴望做某事happen to do sth. 碰巧做某事hesitate to do sth. 犹豫做某struggle to do sth. 努力做某事 二、接不定式作宾补的常用动词 advise sb. to do sth. 建议某人做某事 allow sb. to do sth. 允许某人做某事 ask sb. to do sth.请（叫）某人做某事 cause sb. to do sth. 导致某人做某事 command sb. to do sth. 命令某人做某事 = order sb. to do sth.
2015年高中英语选修六Unit 4作业题6套（人教版有答案和解释）Unit 4 Global warming Period One Warming Up & Reading Ⅰ.用适当的介、副词填空 1．Thatprobablydoesnotseemmuch________youorme，butitisarapidincreasewhencompared________othernaturalchange s. 2．Sohowhasthiscome________anddoesitmatter? 3．Allscientistssubscribe________theviewthattheincrease____ ____theearth’stemperatureisdue________theburning________fo ssilfuels________coal，naturalgasandoiltoproduceenergy. 4．Theproblembeginswhenweaddhugequantities________extracarb ondioxideintotheatmosphere. 5．Weknowthatthelevels________carbondioxidehaveincreasedgre atlyoverthelast100________150years. 6．Hefoundthatbetweentheseyearsthecarbondioxide________thea tmospherewent________fromaround315parts________around370par tspermillion. 7．Theyalsoagreethatitistheburningofmoreandmorefossilfuelst hathasresulted________thisincreaseincarbondioxide. 8．However， theattitudesofscientists________thisrisearecompletelydiffer ent. 9．________theonehand， Dr.Fosterthinksthatthetrendwhichincreasesthetemperatureby5d egreeswouldbecatastrophe. 10．________theotherhand，therearethose，likeGeorgeHambley， whoareopposed________thisviewandbelievethatweshouldnotworry ________highlevelsofcarbondioxide________theair. Ⅱ.佳句翻 译与仿写1．Thereisnodoubtthattheearthisbecomingwarmerandthatitishum anactivitythathascausedthisglobalwarmingratherthanarandombu tnaturalphenomenon. 翻译：
常用口语： 1. I’m not myself！我烦透了！ 2. Don’t bother me！别烦我！ 3. Give me five more minutes, please. 再给我五分钟时间，好吗？ 4. How did you sleep? 你睡的怎么样？ 5. Don’t hog the bathroom! 别占着卫生间了！ 6. Don’t hog the shower! 别占着浴室了！ 7. Don’t hog my girlfriend! 别缠着我的女朋友了！ 8. Get outta there! 快出来！ 9. I will treat you. 我请客。 10. What are you in the mood for? 你想吃什么？ 11. Who is gonna drive? / Who’s driving? 谁来开车？ 12. You know what I mean? 你明白我的意思吗？ 13. Could you run that by me again?
你能再说一遍吗？ 14. So what you are trying to say is... 那么，你想说的是…… 15. Whadja do last night? 昨晚你干嘛去了？ Whadja=What did you 16. Didja have a good time? 玩的开心吗？ didja=did you 17. Where wouldja like to go tonight? 今晚你想上哪儿？ Wouldja=Would you 18. I am running late. 我要迟到了。 19. I’ve gotta get outta here. 我得离开这儿了。 20. I’ve gotta catch the bus. 我要去赶公共汽车了。 21. gotta=got to wanna=want to gonna=going to 22. Yo—taxi! 嗨，出租车！ 23. Where to ? (你)要去哪儿？
补充：英语写作常用句型： 句子写的好坏，是文章写作成败的关键。以下一些惯用句型，实用性较强。 一。开头句型： 1．As far as…is concerned,…就……而论 When it comes to sth/doing sth. 当谈论到…… 1)As far as the role of information in the future is concerned, I believe that information will play a more and more important part in people’s decision-making. 2)As far as what was mentioned above is concerned, how can we ignore the advantages travelling brings forth? 就前面所提及的而言，我们怎么可以忽视旅游带来的裨益呢？ 2．It goes without saying that…不用说 1)It goes without saying that practice makes perfect. 2)It goes without saying that reading makes a full man. 3. It can be said with certainty that…可以肯定的说 1)It can …… that cultivating a hobby can add fun to our life. 2)It can ….… that because of the knowledge, we can now enjoy a comfortable life which is brought about by advanced technology. 可以肯定地说，正由于知识我们才能享受科技进步所带来的舒适生活。 4. As the proverb says, …有句谚语说 As the saying gose, …俗话说 As the saying puts it, …俗话说 1) As the proverb says, “Honesty is the best policy.”诚实为上策。 2) As………goes, “Diligence makes up for deficiencies.”俗话说：“勤能补拙”。 3)An English proverb says, “Lost time is never found again.” 英国有句谚语说的好：“光阴如流水，一去不复回。” 5. It has to be noticed that …必须注意的是…… 1)It has to be noticed that the air we breathe is already seriously polluted by the exhaust factories and vehicles give off. 必须注意的是：我们呼吸的空气已经被工厂和交通工具所释放的废气严重污染了。 2) It has to be noticed that market all over the country are swamped with fake and poor quality products and this has greatly harmed the state’s interests and people’s health. 必须注意的是：假冒伪劣的产品充斥全国市场，这种情况大大损害了国家利益和人 民的健康。 6. It’s generally recognized that …人们普遍认为 1) It’s generally recognized that college students shouldn’t try to reach after what is beyond their grasp when they choose to find a good job after graduation.人们普遍认为大学生 在大学毕业后想找一个好工作时，不应该追求超出他们能力以外的目标。 2)It’s generally recognized that lazy hands makes a man poor, while diligent hands bring
专业四级辅导：s Test Eight It is the first time +that分句 在“It is/was/will be the first time+that分句”结构中，当主句动词为is/will be 时，that分句动词一律用现在完成体，引导词that可以省略。例如： It is the first time I’ve been here. Don’t forget, it’ll be the first time I’ve spoken in public. 当主句动词为was时，that分句动词通常用过去完成体。例如： It was the first time she’d been at a summer school and she thoroughly enjoyed it. 近义词辨析 fast, hasty, quick, rapid, speedy, swift 这组词均含有“迅速的”，“快捷的”的意思。 fast 强调速度快，且保持不变；又指钟表的时间超过准确的时间。 We took a fast train to Beijing.我们坐快车来北京。 hasty 指匆忙、急促，涉及因此而引起的慌乱、疏漏。 Don’t arrive at hasty conclusions.别匆忙下结论。 quick 强调动作、行为发生得突然且持续时间短。指人时，暗示聪明、领悟快。 The tiger took a quick leap at the sheep.老虎猛地向羊扑去。
rapid 指就整个过程来讲速度快，但并不一定指这一过程的速度始终均匀不变。 The growth of the economy has been rapid in recent years.近年来，经济增长速度很快。 speedy 指人处理问题迅速或物体运转速度快。 His accusations brought a speedy denial.他的指控马上遭到了否认。 swift 与fast和quick同义，但带有文学色彩。 Eagles are swift in flight.鹰飞得很快。 全真模拟试题 1. It was requested that all of the equipment ____in the agreed time. A. Erected B. would be erected C. be erected D. will be erected 2. The man sitting opposite me smiled dreamily, as if ____something pleasant in the past. A. to remember B. remembered C. having been remembered D. remembering 3. I ____him the Christmas gift by mail because he came home during the Christmas
第一节动词的时态 一、一般现在时： 1、由when、as soon as、the minute、the moment、till、until等引起的时间状语从句，以及由if、unless、provided that等引起的条件状语从句常常用一般现在时态表示将来的动作，而主句则用 一般将来时态。 例：They will go home for winter vocation as soon as they finish their exams. 2、当表示普遍的真理或者众所周知的客观事实，常常用一般现在时态。例：The earth is round. 地球是圆的。 二、一般过去时：区分三个短语的用法： 1、used to do sth：过去常常做某事。 2、be/get used to doing sth：习惯做某事。 3、be used to do sth：被用于做某事。 三、一般将来时： 1、be to+动词原形：表示安排或计划好了的动作。例：The Third-Ring Road is to be open to traffic before National Day. 2、be about to+动词原形：表示即将发生的动作。例：The lecture is about to begin.讲座即将 开始。 3、一些表示动作趋势，如开始、终结，以及一些表示动作方向，如往来的动词，常常用现在进行 时态表示按照安排将于将来发生的事情，这类动词常见的有如：start，go，leave，come，arrive等。例：We are leaving for Beijing tomorrow. 我们明天动身去北京。 四、进行时态： 重点区分when和while引起的时间状语的用法。 When表示时间上的点，在考试中其引导的时间状语从句多翻译为“这时？”，主句多用进行时态；while引导的时间状语从句多翻译为“正当……时”，该从句用进行时态。例：One of the guards was sleeping when the general came in, which made him very angry. I fell and hurt myself while I was playing tennis. 五、现在完成时：
中考英语-句子的固定搭配（含答案）-专题练习 一、单选题 1.It's half past seven. It's time to . A. have a breakfast B. have breakfast C. have the breakfast D. has this breakfast 2.I'm looking forward to __________my grandparents this summer holiday. A. see B. sees C. saw D. seeing 3.It takes about 30 minutes _______ a bicycle from my home to school. A. ride B. riding C. to ride D. rides 4.Could you please the dishes? A. to do B. do C. to make D. makes 5.It is very interesting for me ______________ to cook food. A. learned B. learn C. to learn D. learning 6.——I feel a bit hungry now. ——Why not_____ for dinner with us? A. go B. did you go C. to go D. do you go 7.—_______ the weather _______ Hangzhou? —Sunny but cold. A. Where's; of B. What's; in C. How's; in D. How's; of 8.China ________ food and drinks ________ the people in Philippines(菲律宾) last year. A. provided, for B. provides, with C. provided, with D. provides, for 9.It's your turn ________ the classroom. A.clean B.to cleaning C.to clean D.cleans 10.While we down the street, the accident happened. A. walked B. are walking C. were walking 11.She had great difficulty ________ the suitable food on the menu in that restaurant. A. finding B. find C. found D. to find 12.What's with you? A. wrong B. the wrong C. matter D. up 13. When will you return to your hometown? __________. A. Not until the end of this month B. Until next week C. A few days ago D. A few weeks before 14.It usually takes about ten minutes ____to school. A. by bike B. on a bike C. to ride D. ride 15.Xiao Li was supposed __________ her homework before nine o'clock. But she couldn't.
四年级下册英语复习资料 Unit1Myschool(我的学校) 一、单词： 楼层：firstfloor一楼secondfloor二楼 教室：teachers’office教师办公室library图书馆playground操场computerroom 计算机房musicroom音乐教室artroom美术教室gym体育馆 其他：nextto在近旁homework作业class班；班级forty四十way方向 指示代词：this这，这个(通常指空间上离我们较近的单数物品) that那，那个(通常指空间上离我们较远的单数物品) 二、重点句型： 1.询问教室位置：Whereisthelibrary图书馆在哪里？ It’sonthesecondfloor.它在二楼。 2.猜测教室： Isthistheartroom这是美术教室吗？Yes,itis.No,itisn’t. Isthattheteacher’soffice那是…吗Yes,itis.No,itisn’t. Isitacomputer它是计算机吗？Yes,itis.No,itisn’t. Doyouhaveaplayground你们（学校）有操场吗？ Yes,wedo.No,wedon’t. Howmanystudentsarethereinyourclass你班有多少个学生？ Forty-fivestudents.四十五个学生。 礼貌待客“这边请”Thiswayplease. P5：Let’sdo部分： Gotothelibrary.Readabook.去图书馆，读书。
Gototheteacher’soffice.Sayhello.去教师办公室，说您好！Gototheplayground.Playfootball.去操场，踢足球。Gotothegarden.Watertheflowers.去花园，浇花。 三、四会单词和四会句子 P9:Thisisthelibrary.Thatistheplayground. 这是图书馆。那是操场 Unit2Whattimeisit(几点钟了) 一、词汇（另外要根据时间判断相应的活动a.m.上午p.m.下午）名词词组： 一日三餐：breakfast早餐lunch午餐dinner晚餐 课程：musicclass音乐课PEclass体育课Englishclass英语课 动词词组：getup起床gotoschool去上学gohome回家 gotobed上床睡觉 二、重点句型: 是时候该It’stimefor+名词词组.It’stimeforEnglishclass. 干什么了：It’stimeto+动词词组.It’stimetogotoschool. 询问时间： Whattimeisitnow现在几点钟了？ It’s5o’clock.5点了。 P15：Let’sdo部分. Timeforbreakfast.Let’sdrinksomemilk. 到吃早餐的时间了。让我们喝些牛奶吧。 Timeforl unch.Let’shavesomechicken.
五种基本句型 句子就是由主语、谓语动词、表语、宾语、宾语补足语等组成得,依其组合方式可分为五种基本句型,如下表所示： 注意句子成分得表示法Ｓ:Ｓｕbject(主语) V:Verｂ(动词)O: Ｏbjｅct（宾语) P：Ｐrｅdiｃａtive(表语) OＣ: Oｂｊeｃｔplement(宾语补足语) 五种基本句型见下表： 第１种S+V主＋谓 第2种S+V+Ｏ主+谓+宾 第３种Ｓ+V＋P 主+谓+表 第 4 种S+V+o(间接宾语)＋Ｏ（直接宾语） 第 5 种S+Ｖ＋O＋OC 主+谓＋宾+宾补 第 1 种句型:主语+不及物动词:S+Ｖ?Ｂirｄs fly、鸟飞、--－-- －-主语谓语（不及物动词) Ｈｅrｕns in ｔｈe park、她在公园里跑、----－- -－－－---－--－--主语谓语地点状语(不及物动词)? 此句型就是主语＋不及物动词构成句子得主体部分。不及物动词,后面当然不能直接带宾语了，要补上相应得介词,但就是可以有状语来修饰。上例中得iｎｔｈe ｐark,就是地点状语。 Ｃlass begins、(bｅgin 在句中就是不及物动词) 开始上课。 比较ｗe ｂegiｎOｕｒcｌaｓs at eｉｇht、我们八点钟开始上课。该句属于第 2 种句型,bｅgｉn 在句中就是及物动词，由此可见有些动词既可作及物动词也可以作不及物动词。 第 2 种句型:主语＋及物动词+宾语:S+V＋O My fatｈｅｒreaｄtｈｅｂooｋ、 我父亲读过那本书、?(及物动词)?注意有些不及物动词后面加上介词就可把它瞧成一个及物动词，后面就可以加宾语了。Ｙou mｕst ｌｉｓten ｔｏmｅ、您必须听我得。(Liｓtｅn 就是不及物动词。但加上ｔo 之后,Ｌistｅn ｔｏ可以瞧成一个及物动词) 后面直接带宾语得动词就是及物动词，名词与名词得相当语(如代词、不定式、动名词……)等都可充当宾语。Ｓｈeｌikｅs Engｌisｈ、（名词作宾语） I knｏｗhim vｅrｙwell、(代词作宾语) (同第一种句型一样,本句型可以有状语、定语修饰）Thｅｙwant ｔo gｏ、(不定式作宾语） Hｅstopｐeｄwｒiting、(动名词作宾语) ?第3 种句型:主语＋系动词+表语:S+Ｖ+P Ｈe ｂｅcａme a ｓｃienｔisｔ、她成为一个科学家了?谓语(系动词) be 动词与ｂee 就是英语中常见得系动词,后面必须接表语,才能用来说明主语,表示“…… 就是……”,“……变成……”等意思。 表语通常就是名词或形容词等。Tｈｅy are honｅst、她们就是诚实得。 Hｅｂecameａsｃiｅntisｔ、她成为了一个科学家。 His face goes reｄ、她得脸变红了。Ｉt grew dark、天变黑了。 注意在英语中,除了bｅ动词与bee 属于系动词外，还有一些实义动词,当表示状态存在或表示状态变化时也可以作系动词。这些词有:keeｐ、lｏok 、
英语最基础的语法句型有哪些 英语语法是针对英语语言进行研究后，英语语法系统地总结归纳出来的 一系列语言规则。英语语法的精髓在于掌握语言的使用。 1 英语五种基本句型结构一、句型1：Subject (主语) ＋Verb (谓语) 这种句型中的动词大多是不及物动词，所谓不及物动词，就是这种动词后 不可以直接接宾语。常见的动词如：work, sing, swim, fish, jump, arrive, come, die, disappear, cry, happen 等。如： 1) Li Ming works very hard.李明学习很努力。 2) The accident happened yesterday afternoon.事故是昨天下午发生的。 3）Spring is coming. 4) We have lived in the city for ten years. 二、句型2：Subject (主语) ＋Link. V(系动词) ＋Predicate(表语) 这种句型主要用来表示主语的特点、身份等。其系动词一般可分为下列两 类： (1)表示状态。这样的词有：be, look, seem, smell, taste, sound, keep 等。如： 1) This kind of food tastes delicious.这种食物吃起来很可口。 2) He looked worried just now.刚才他看上去有些焦急。 (2)表示变化。这类系动词有：become, turn, get, grow, go 等。如： 1) Spring comes. It is getting warmer and warmer.春天到了，天气变得越来越暖和。 2) The tree has grown much taller than before.这棵树比以前长得高多了。
2011三星笔试固定搭配必背句型 固定搭配必背句型 1. allow sb to do sth 允许某人去做某事（后接动词不定式） My father allowed me to go out for a walk after finishing my homework. 2. asked sb (not) to do sth 叫某人做事某事（叫某人不要去做某事） My father asked me to study hard. He asked me not to swim alone. be asked to do sth 被叫去做某事/被邀请去做某事 I was asked to have a dinner with them yesterday. 3. be afraid to do sth 害怕做某事 She is afraid to ask me questions. 4. be afaid of doing sth 害怕做某事 I am afraid of going out at night. 5. be afaid of sth 害怕某物 He is afraid of snakes. 6. be amazed to do sth 对做某事感到惊讶 He was amazed to meet the girl there. be amazed at sth 对某事感到惊讶 they were amazed at the news. 7. be busy doing/with sth 忙于做某事（常考） I was busy washing my car at that time. 那时候我正忙于清洗我的车子。 I am busy with my work. 8. be coming/going/leaving/fiying/moving/dying（某些位移动词用进行时态时表将来） the bus is coming/the dog is dying. 9. be excited to do sth 对做……感到兴奋 Jacky was excited to travel there by plane. be excited at sth Lily was excited at his words. be excited about doing sth he was excited about passing the exam without going overing books. 10. be frightened to do sth 害怕去做某事 Sam is frightened to ride a horse. 11. be glad/happy to do sth 高兴去做某事 she is happy to clean the blackboard with me. be pleased to do sth高兴做某事 she was pleased to help the old man yesterday. be pleased with sth 对某事感到高兴/满意 the teacher was pleased with my answer. 12. be interested in sth/doing sth 对某事感兴趣/对做某事感兴趣 she is interested in swimming in the river. My btother is interested in Chinese. 13. be/get ready for/to do sth Be ready for sth 为某事做好了准备 We are ready for the exam.
五种基本句型 句子由主语和谓语两大部分组成。主语结构比较单一，谓语结构则不然，不同类别的谓语动词导致不同的谓语结构，从而形成了不同的句型（Sentence Pattern）。换句话说，不同的句型是由不同类别的谓语动词所决定的，因此，句型又被称为动词句型（Verb Pattern）。语法家们对句型的分类不尽相同，一般认为，现代英语的基本句型主要有五种： 1．“主----系-----表”（SLP）句型： 在这种句型中，谓语动词是以be为主的连系动词（Linking Verb），后面跟主语补语（Subject Complement），如： These oranges have kept fresh. 这些桔子一直很新鲜。 Mary is a student / here /in the room. 玛丽是个学生/在这儿/在房间里。 有的语法家把be后面的副词（短语）或介词短语视为状语，从而形成了“主----动-----状”（SVA）这一在五种基本句型之外的句型（见上面最后一个例句）。 2．“主----动”（SV）句型： 在这种句型中，谓语动词为不及物动词（Intransitive Verb），谓语部分通常只包括限定动词，即使有状语，也属任意性状语，即：去掉后并不影响句子结构和意义的完整，如：This bread won’t keep (for a long time). 这种面包不好（长期）存放。 Tom has left. 前面说过,有些句子中的状语是不可缺少的，这种状语被称为必具性状语，从而构成“主 ----动----状”(SVA)句型，但这仅限于少数几个动词的某些用法，因而不是一种主要句型，如： They are staying in a hotel. 他们暂住在一家旅馆里。 3．“主----动-----宾”（SVO）句型： 在这种句型中，谓语动词为只带一个宾语的及物动词，这种动词被称为单宾语及物动词（Monotransitive Verb），如： He kept the money. 他保存着这些钱。 They have left the hotel. 他们已经离开了那家旅馆。 在这种句型中，状语通常也不是必不可少的，但有少数几个及物动词的某些用法要求必具性状语，从而形成了“主----动-----宾-----状”（SVOA）这一在五种基本句型之外的另一种句型，如： The train leaves London at nine. 这列火车九点钟驶离伦敦。
I It is high time that you went to bed. 该是你睡觉的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime they arrived. 他们到得正是时候。 https://www.doczj.com/doc/b318840144.html, Itishightime to be setting our faces towards reconstructing our country. 现在正是我们着手重建家园的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime that we implemented the reform. 是实施改革的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime that we had our lunch. 该是我们吃午饭的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime that such practices were ended. 该是结束这种做法的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime that we began the meeting. 正是我们开会的时间了。 119.75.215.166 Itishightime to begin our plan. 该是开始我们计划的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime that all the chinese people realized the harm of piracy. 是到了全中国人意识到盗版危害的时候。
https://www.doczj.com/doc/b318840144.html, Itishightime we did something to stop air pollution. 我们该做些事来防止空气污染了。 https://www.doczj.com/doc/b318840144.html, Itishightime to establish the management committee. 现在的确是该成立管理会的时候了！ https://www.doczj.com/doc/b318840144.html, Itishightime that we should urge an immediate end to this deplorable phenomenon. 该是到立即结束这种可悲现象的时候了。 https://www.doczj.com/doc/b318840144.html, Itishightime for us to destroy the blandishments in the commercial advertisements. 现在是时候了，我们摧毁花言巧语的商业广告。 https://www.doczj.com/doc/b318840144.html, Itishightime that mr uribe let his country begin the stringent preside ntial debate it so badly needs. 是时候乌里韦让国家迫切需要开展严格的总统辩论。 118.126.4.64 Itishightime that the issue were to be solved so as to promote the economic development. 为了促进经济发展到该解决问题的时候了。 119.75.215.166 Obviously, itishightime that we took some measures to solve the problem. 显然，这正是需要用我们用一些方法解决这个问题的时候了。 https://www.doczj.com/doc/b318840144.html, Just as parents struggle to teach their children to think ahead, to choose a future and not just drift through life, itishightime that human society as a whole learns to do the same. 正如做父母的总试图教育他们的子女不能浑噩度日，而应该向前看，选择自己的前途，整个人类社会也早该学会这样做了。 https://www.doczj.com/doc/b318840144.html, Itis important to keep credit card balances at a reasonable level, no matter how high the top line balance permitted is at any given time. 讲信用卡债务保持在一个合理的水平，无论信用额度可以达到多高。 https://www.doczj.com/doc/b318840144.html,