2016屆高考英語語法知識情態動詞和虛擬語氣復習
everyone_____get out.a.had to b.would c.could d.was able to表示“推斷、判斷”的canmay,must在肯定句中都可以用來表示可能。在含義上must語氣最肯定,may表示的是事實上的可能性。peter______come with us tonight, but he isn’t very sure yet.a.must b.may c.can d.will而can表示的是邏輯上的可能性：mary is in poor health. she can be ill at any times.在否定句中只能用can和may。所以can’t時用以代替mustn’t，語氣比may更肯定。中文可以翻譯為不可能。michael______be a policeman, for he’s much too short.a.needn’t b.can’t c.should d.may在疑問句只能用can，不能用may和must。he may be very busy now. can he be very busy now?he must be very busy now. can he be very busy now?needneed作為情態動詞只有一種形式，只用于否定句和疑問句。
daredare作為情態動詞用時有兩種形式：dare和dared兩個詞形，除了可以用于否定句和疑問句外，還可以用于條件從句或表示懷疑的句子中。if he dare come,i will kick him out. i don’t know whether hedare say.注意:he doesn’t dare(to)answer the question.（否定句）does she dare(to)enter the dark room?（疑問句）shall用于第一人稱：征求對方的意見。what shall we do this evening?用于第二、三人稱：警告、命令、允諾、威脅等。you shall fail if you don’t work harder. 警告he shall have the book when i finish reading.允諾he shall be punished.威脅
should勸告、建議、命令、應該做、道義上的責任。you should(ought to) go to class right away. i should(ought to) help him because he is in trouble.
will/would請求、建議，would比will委婉客氣。would you pass me the book?表示意志、愿望和決心。i will never do that again. they asked us if we would do that againwould可表示過去反復發生的動作或某種傾向。during the vacation he would visit me every weekthe wound would not heal.（傷口老是不能愈合）would表示估計或猜想。it would be about ten when he left home. what would she be doing there?情態動詞+have done的用法could+have done：本可以做而實際上未能做。you could have done better, but you didn’t try your best.cannot+ have done：表示對現在或過去行為的否定推測。he cannot have been to that town.can+主語+ have done：表示對過去行為的懷疑或不肯定（用在疑問句中）。can he have got the book?