2019年高考英語二輪專題復(fù)習6情態(tài)動詞和虛擬語氣
johnny, you_____play with the knife, you_____hurt yourself.
a. won’t/can’t b.mustn’t/may c.shouldn’t/must d.can’t/shouldn’t
③在肯定句中could不可以用來表示過去某一特定場合的能力，而要用was/were able to。
如不可以說：they could jump into the sea before the boat was blown up
而要說：they were able to/managed to jump into…
the fire spread through the hotel very quickly but everyone_____get out.
a.had to b.would c.could d.was able to
但在否定句中could/was(were)able to可以通用:
i couldn’t/wasn’t able to see him yeaterday.
④表示許可時用may/can都可以。只不過用may時較側(cè)重講話人的許可，而can較側(cè)重客觀情況的許可，must則表示必須做某事。
2.表示“推斷、判斷”的can,may,must
①在肯定句中都可以用來表示可能。在含義上must語氣最為肯定,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.
②在否定句中只能用can和may。此時can’t用以代替mustn’t，語氣比may not更強。can’t中文可以翻譯為“不可能”、may not中文可以翻譯為“可能不”。
michael______be a policeman, for he’s much too short.
a.needn’t b.can’t c.should d.may
③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?
3.表示“請求、提議”（用在疑問句中）的can和could，這時could比can語氣更婉轉(zhuǎn)
can（could）you give me a lift to the station?
你（您）能不能讓我搭你（您）的車去車站呀？
4.表示“驚訝、懷疑”（用在疑問句中）的can和could，這時could比can語氣更婉轉(zhuǎn)
who can it be at this time of day?這個時候到底會是誰呢？
5.構(gòu)成下列特殊句式的can
①can not/can never…too… cannot…enough“無論怎么……也不為過分，越……越好，非常……”
since it is a good thing,we cannot do it too soon.
既然是好事情，我們越早開始做越好。
②can’t help doing…,cannot help but do…,cannot but do…“禁不住，不由得，不得不”