高三英语一轮复习情态动词教学课件(25张).ppt
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* Grammar Modal verbs 情态动词 情态动词的语法特征 1)?情态动词?不能单独做谓语,它与其他动词构成谓语时,总是放在其他动词之前。 3)?情态动词没有人称,数的变化,但有些情态动词,如can、will也有一般式和过去式的变化。 4)?情态动词的“时态”形式并不是时间区别的主要标志,不少情况下,情态动词的现在式形式和过去式形式都可用来表示现在时间、过去时间和将来时间。 2)除ought 和have?外,后面只能接不带to?的不定式。 1) Some of us can use the computer now, but we couldn’t last year. 2) The new-built theatre can seat 1500 people. 3) Can she be in the computer center? 4) I though what he said could not be true. can在肯定句中表可能性时,表示理论上的可能性。 Even expert can make mistakes. He can be very friendly at times.“有时候会……” 5) Can/Could I use your dictionary? 6) Could you lend me a hand? 1.表能力 3. 表示“请求” “允许”(表请求时,口语中常用 could 代替 can 使语气更委婉,回答时用can) 2. 表示推测,意为“可能”“或许”,用于疑问句或否定句 1. can 与could 4. 表示“许可”,可与may 换用。 You can go home now. 5. can 用于疑问句或否定句中时,表惊异、不相信等, 意思是“可能、能够”。 Can this news be true? How can you be so foolish? 6. can’t/ couldn’t +have + done 表示对过去情况的否定推测 Susan can’t have written a report like this. 7. could + have + done 表示对过去能做而未做的事情 感到惋惜,遗憾 It’s a pity. Your class could have got the first prize. can, could 和be able to的用法 She can/be able to sing the song in English. This machine can make you feel comfortable. 1.can, be able to都可表示“能力” can的主语是人或物,be able to的主语是人 We’ll be able to finish the work soon. I haven’t been able to see the film. 2.can只用于现在式和过去式(could)。 be?able?to可以用于各种时态。 could用于表示泛指过去的能力。如: I?could?read?when?I?was?four. Although the soldier was badly wounded, he was able to tell what had happened. She ran fast but she couldn’t /wasn’t able to catch the bus. 3.表示特定的某一过去能力或表示成功地做了某事时,只能用was/were?able?to,?不能用could。 He?was?able?to?flee?Europe?before?the?war?broke?out. ?? He?was?able?to?swim?halfway?before?he?got?tired. 表示过去的能力 注意can的惯用语 1.cannot (help/choose) but do… 2.can but do 3.cannot help doing 4.can’t help sb. doing sth. 5.can’t help sb. do sth. 6.can’t help (it) 7.cannot too 不得不,只能 只好,不得不 忍不住 不能让某人不做某事 不能帮忙做某事 控制不住,没有办法 越…越好 2. may 与might 1.
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