bevi 現(xiàn)在時(shí) I am, you are, he is, we are, you are, they are （縮略式 I'm, you're, he's, we're, you're, they're）, （否定縮略式 I'm not, isn't, aren't）, 過去時(shí) I was, you were, he was, we were, you were, they were （過去時(shí)否定縮略式 wasn't, weren't）, 過去分詞 been, 現(xiàn)在分詞 being“Be”除了原形的“be”之外,還有另外七種形式：am, is, are, been, being, was, were. 在句子中,“be”可以是主動(dòng)詞或助動(dòng)詞
1）協(xié)助主要?jiǎng)釉~構(gòu)成謂語動(dòng)詞詞組的詞叫助動(dòng)詞.被協(xié)助的動(dòng)詞稱作主要?jiǎng)釉~構(gòu)成時(shí)態(tài),語態(tài). 助動(dòng)詞是語法功能詞,自身沒有詞義,不可單獨(dú)使用,它沒有對(duì)應(yīng)的漢譯,例如： He doesn't like English. 他不喜歡英語. （doesn't是助動(dòng)詞,無詞義；like是主要?jiǎng)釉~,有詞義) 2） 助動(dòng)詞協(xié)助主要?jiǎng)釉~完成以下功用,可以用來： a. 表示時(shí)態(tài),例如： He is singing. 他在唱歌. He has got married. 他已結(jié)婚. b. 表示語態(tài),例如： He was sent to England. 他被派往英國. c. 構(gòu)成疑問句,例如： Do you like college life? 你喜歡大學(xué)生活嗎? Did you study English before you came here? 你來這兒之前學(xué)過英語嗎? d. 與否定副詞not合用,構(gòu)成否定句,例如： I don't like him. 我不喜歡他. e. 加強(qiáng)語氣,例如： Do come to the party tomorrow evening. 明天晚上一定來參加晚會(huì). He did know that. 他的確知道那件事. 3） 最常用的助動(dòng)詞有：be, have, do, shall, will, should, would
首先它是動(dòng)詞,而且不同于行為動(dòng)詞,行為動(dòng)詞表示的是可以通過行為來表達(dá)的動(dòng)作（如寫,讀,跑）,而情態(tài)動(dòng)詞只是表達(dá)的一種想法（如能,也許,敢）. 用法是：情態(tài)動(dòng)詞+行為動(dòng)詞原形 例句：I can read this sentence in English. 我能用英語讀這句話. 情態(tài)動(dòng)詞是一種本身有一定的詞義,表示說話人的情緒,態(tài)度或語氣的動(dòng)詞,但不能單獨(dú)作謂語, 只能和其他動(dòng)詞原形構(gòu)成謂語. We can be there on time tomorrow.我們明天能按時(shí)去那兒. May I have your name? 我能知道你的名字嗎? Shall we begin now?我們現(xiàn)在就開始嗎? You must obey the school rules.你必須遵守校規(guī). 情態(tài)動(dòng)詞數(shù)量不多,但用途廣泛,主要有下列: can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would),have (to) ,had better. 情態(tài)動(dòng)詞還有一個(gè)很重要的用法,即情態(tài)動(dòng)詞表推測—— 情態(tài)動(dòng)詞表推測的用法小結(jié) （一）情態(tài)動(dòng)詞表推測的三種句式 1.在肯定句中一般用must (一定),may（可能）,might / could（也許,或許）. （1）He must/may/might know the answer to this question? 他一定/可能/也許知道這個(gè)問題的答案. （2）It is cold in the room. They must have turned off the heating. 屋里很冷,他們肯定把暖氣關(guān)了. 2.否定句中用can’t / couldn’t(不可能), may not/might not(可能不). （1）It can’t/couldn’t be the headmaster. He has gone to America. 這不可能是校長,他去美國了. （2）He may not/might not know the scientist. 他也許不認(rèn)識(shí)那位科學(xué)家. 3.疑問句中用can/could (能……?). （1）Could he have finished the task? 他可能把任務(wù)完成了嗎? （2）Can he be at home now? 他現(xiàn)在能在家嗎? 注：以上三種句式中情態(tài)動(dòng)詞的語氣按程度都是依次遞減的.Might, could并非may, can的過去式,而表示語氣較為委婉或可能性較小. （二）情態(tài)動(dòng)詞表推測的三種時(shí)態(tài) 1.對(duì)將來情況的推測,用“情態(tài)動(dòng)詞 + 動(dòng)詞原形”. （1）She must / may / might / could arrive before 5. 5:00前她一定/可能/也許到. （2）She must/may/might/could walk miles and miles among the hills without meeting anyone. 她一定/可能/也許會(huì)在山里一連走好幾英里而遇不到一個(gè)人. 2.對(duì)現(xiàn)在或一般情況的推測,用“情態(tài)動(dòng)詞 + be”,“情態(tài)動(dòng)詞 +be doing”或“情態(tài)動(dòng)詞 + 動(dòng)詞原形”. （1）He must / may / might / could be listening to the radio now. 他一定/可能/也許正在聽收音機(jī). （2）He can’t ( couldn’t ) / may ( might ) not be at home at this time. 這個(gè)時(shí)候他不可能/可能不在家. （3）Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony ? 布什先生一向準(zhǔn)時(shí),這次開幕式他怎么可能遲到呢? 3.對(duì)過去情況的推測,用“情態(tài)動(dòng)詞 + have +過去分詞”. （1）It must / may / might / could have rained last night .The ground is wet. 地濕了,昨晚肯定/可能/也許下雨了. （2）The door was locked. He can ( could ) not / may ( might ) not have been at home . 門鎖著,他不可能/可能不在家. （3）Can / Could he have gotten the book? 難道他找到書了嗎? 注：情態(tài)動(dòng)詞 should /ought to表推測時(shí),意為“想必會(huì),理應(yīng)……”但與“have +過去分詞”連用時(shí),則又可構(gòu)成虛擬語氣意為“本應(yīng)該做某事卻沒做”.例如： （4）It’s seven o’clock. Jack should/ought to be here at any moment. 現(xiàn)在七點(diǎn)鐘了,杰克理應(yīng)隨時(shí)到達(dá).（推測） （5）She should / ought to have attended your birthday party, but she had to look after her mother in hospital. （虛擬） 她本該出席你的生日晚會(huì)的,可是她得在醫(yī)院照顧她媽媽. （6）Tom should not /ought not to have told me your secret, but he meant no harm. （虛擬） 湯姆本不該告訴我你的秘密,可是他并無惡意.