bookU grammar.pptVIP

* * Grammar Modal verbs 情态动词 (I) Unit1 Festivals around the world ·情态动词的语法特征 1）?情态动词?不能单独做谓语，除ought ?和have?外，后面只能接不带to?的不定式。 2）?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。 3）?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。 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 Could I have a look at your notebook? Yes , you can./No,?you?cant. 4.could不表示时态 ,表示委婉的请求，（注意在回答中不可用could）。 Can this news be true? How can you be so foolish? It can’t be Mary. She has fallen ill. 5.表示“惊异,怀疑,不相信”的态度(主要用于否定句,疑问句和感叹句中) Linda didn’t catch the train. She could have caught it. Dont?worry. They?could?have?just?forgotten?to?phone. 6.表示推测，译为“可能、或许”，can常用于否定句(意思是不可能已经)和疑问句；could除用于否定句及疑问句外,还可用于肯定句(意思是那时可能;本来可以)。 may和might ---May I use your pencil? ---Yes, you may./ No, you mustn’t. 1. may和might 用于一般问句中表示委婉的请求,肯定回答用may,否定用mustn’t She may not be working now. John might be at home now. 2. may和might表示“可能性”, may/might + v 指现在或将来可能发生的动作情况。might暗示的可能性更小 She may/might have gone to the cinema. They may/might not have received our telephone. 3.对过去发生的事情的可能性作出判断用may/might have done,用might比用may的可能性更小 May you succeed! May?God?bless?you! 4.may?放在句首祈使句，表示祝愿。 Will 和 would If you will help me with my English, I will be very happy. I promised that I w