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1.構(gòu)成: have / has been doing

3.現(xiàn)在完成時與一般過去時的區(qū)別:

①.現(xiàn)在完成時和一般過去時所表示的動作都發(fā)生在過去, 但前者將過去的動作與現(xiàn)在的結(jié)果或?qū)ΜF(xiàn)在的影響聯(lián)系起來, 而后者只限于表示過去的動作本身, 與現(xiàn)在無關(guān)

②.現(xiàn)在完成時不能與表明確時間的狀語如: yesterday, last year, two days ago, when I came in等連用, 但可與表示不明確時間的狀語如: already, yet, sometimes, often, before, lately, recently, once, twice, ever等連用, 也可以和包括現(xiàn)在在內(nèi)的時間狀語如: this morning, today, this week, this year等連用

　　　　 a. She has already come.

　　　　 b. I have met him before.

　　　　 c. Ma Hong has always been a good student.

　　　　 d. Have you ever been to the Great Wall ?

　　　　 e. I have seen him this morning.

2.用法:

①.表示動作在說話之前己經(jīng)完成, 而后果或影響至今仍存在

　　　　 a. He has gone to Shanghai. ( =He went to Shanghai and he is not here now. )

　　　　 b. I have opened the window. ( =I opened the window and the window is now open.)

　　　　 c. The concert has started. ( =The concert started and is now going on. )

　　　　 d. I have had breakfast. (=I had breakfast and I am not hungry now. )

　　 ②.表示開始于過去, 持續(xù)到現(xiàn)在(也許還會繼續(xù)進(jìn)行下去)的動作或狀態(tài), 用于延續(xù)性動詞, 且句中常帶有表示段時間的時間狀語

　　　　 a. I have studied English since 1987.

　　　　 b. He has lived here for two years.

　　　　 c. He has been ill for ten days.

1.構(gòu)成: have / has done

2.用法:

　 　①.表示說話時正在進(jìn)行著的動作, 或現(xiàn)階段正在進(jìn)行而說話時不一定正在進(jìn)行的動作

　　　 　　a. I am writing a letter.

　　　 　　b. My mother is making a dress these few days.

　 �、�.表示即將發(fā)生的動作(如在最近按計劃或安排好要進(jìn)行的動作), 常見的有這種用法的動詞有: come /go / leave / start / arrive等, 常與表示將來時間的狀語連用

　　　 　　a. They are going to Shanghai on Friday.

　　　 　　b. John is coming here next week.

　 �、�.現(xiàn)在進(jìn)行時動詞與always, continually, constantly等連用, 表示反復(fù)出現(xiàn)的或習(xí)慣性的動作

　　　 　　a. The little boy is always asking questions.

　　　 　　b. You are always saying that sort of thing.

　 　④.在一定的上下文中, 前一句用一般現(xiàn)在時動詞表述現(xiàn)在發(fā)生的事實, 后一句用現(xiàn)在進(jìn)行時動詞來闡述這一事實的原因, 結(jié)果, 目的等

　　　 　　a. He frowns. He is worrying about his boy.他皺著眉頭, 因為他在為他的孩子擔(dān)心. (is worrying表示原因)

　　　 　　b. She criticizes him. She is trying to correct his wrong habits. 她批評他, 想糾正他的壞習(xí)慣. (is trying表示目的)

　　　 　　c. She lets her child have his own way. She is spoiling him. 她不管她的孩子, 把他慣壞了. ( is spoiling表示結(jié)果)

　 �、�.不表示持續(xù)的行為, 而表示知覺, 感覺, 看法, 認(rèn)識, 感情, 愿望或某種狀態(tài)的動詞通常不用現(xiàn)在進(jìn)行時, 如: see, hear, smell, taste, recognize, notice, forget, remember, understand, know, believe, suppose, mean, think, love, hate, care, like, dislike, worry, forgive, want, wish, hope, refuse, feel like, belong to , possess, own, have, be, seem等

1.構(gòu)成: am / is / are doing

2.用法:

　 �、�.表示現(xiàn)狀, 性質(zhì), 狀態(tài), 經(jīng)常的或習(xí)慣性的動作

　　　 　　a. It is fine today.

　　　 　　b. I am a student.

　　　 　　c. I get up at six every day.

d. My father never takes a bus; he walks to his office.

　 �、�.表示客觀事實或普遍真理

　　　 　　a. Japan is to the east of China.

　　　 　　b. The sun rises in the east.

　　　 　　c. A horse is a useful animal.

　 �、�.表示將來確定會發(fā)生的動作(如己安排好或計劃好的動作或按時刻表將來一定會發(fā)生的動作), 可以這樣使用的動詞有: go, come, leave, start, arrive等

　　　 　　a. My train leaves at 6:30.

　　　 　　b. The football match is played the day after tomorrow.

　 　④.在時間和條件狀語從句中可用一般現(xiàn)在時動詞代替一般將來時動詞

　　　 　　a. I will let you know as soon as I hear from him.

　　　 　　b. We will go if it is fine tomorrow.

　　　 　　c. I will be away when he arrives.

　　　 　　d. We shall not begin the discussion until he arrives.

　　　 　　e. Mother, I won’t go out unless you agree.

　　　 　　f. Don’t try to run before you begin to walk.

　 �、�.在某些以here / there開頭的句子中用一般現(xiàn)在時動詞表示現(xiàn)在正在發(fā)生的動作

　　　 　　a. Here comes the bus.=The bus is coming.

　　　 　　b. There goes the bell.

　 　⑥.在體育比賽過程中, 解說員敘述迅速, 短暫動作時, 可用一般現(xiàn)在時, 表示正在進(jìn)行的或剛剛發(fā)生的動作

　　　 　　a. Ma Lianbao passes the ball to Mu Tiezhu, Mu shoots – a fine shot !

　 �、�.在劇本或圖片的說明文字中, 用一般現(xiàn)在時表示動作

　　　 　　a. When the curtain rises, Juliet is sitting at her desk. The phone rings. She picks it up and listens quietly.

1.構(gòu)成: 通常以動詞原形表示. 主語為第三人稱單數(shù)時, 則用動詞的第三人稱單數(shù)形式來表示

8.已知

(1)　　 若x∈R，求f(x)的單調(diào)遞增區(qū)間；

(2)　　 若時，f(x)的最大值為4，求的值

[解](1)由

使

,解得,

(2)由f(x),因此f(x)在上的最大值為+3，使+3=4,　 =1.

6.化簡

并求函數(shù)的值域和最小正周期和遞增區(qū)間.

解：

所以函數(shù)f(x)的值域為，最小正周期

由.(k∈Z)

(2006上海) 求函數(shù)的值域和最小正周期.

[解] 　

　∴ 函數(shù)的值域是,最小正周期是；

(2005重慶卷)若函數(shù)的最大值為，試確定常數(shù)a的值.

解：

因為的最大值為的最大值為1，則

所以