must, can, could, may, might, ought to, had better等只作情态动词;need, dare用于否定句、疑问句是情态动词,用于肯定句是行为动词;shall, should, will, would既可作情态动词也可作助动词;have to, used to, would like to, would rather具有情态动词的某些特征。
【考例1】 My room is a mess, but I ______ clean it before I go out tonight. I can do it in the morning.
A. daren’t B. shouldn’t
C. needn’t D. mustn’t
解析:C。
句意:我的房间很乱,但是在今晚外出之前我不需要打扫它,我可以明天早晨打扫。daren’t不敢;shouldn’t不应该;needn’t不需要,没必要;mustn’t绝不能。
【考例2】 Samuel, the tallest boy in our class, ______ easily reach the books on the top shelf.
A. must B. should
C. can D. need
解析:C。
句意:塞缪尔是我们班里最高的男孩,他可以轻松够到书架顶层的书。must一定;should应该;can能够;need需要。
【考例3】 You ______ be careful with the camera. It costs!
A. must B. may
C. can D. will
解析:A。
因为很贵重,所以“必须”要小心。
1. 对现在或将来的推测用“情态动词+动词原形”。
2. 对过去事情的推测,用“情态动词+have+done”。
【考例1】 You ______ be Carol. You haven’t changed a bit after all these years.
A. must B. can C. will D. shall
解析:A。
这么多年没变,见后猜测一定是卡罗。
【考例2】 George _________ too far . His coffee is still warm .
A. must have gone
B. might have gone
C. can't have gone
D. needn't have gone
解析: C。
句意:乔治不可能走得太远,他的咖啡还热着呢。can’t have done是对过去的否定推测。
【考例3】You ______ feel all the training a waste of time, but I’m a hundred percent sure later you’ll be grateful you did it.
A. should
B. need
C. shall
D. may
解析:D。
你(目前)可能会觉得所有的训练是在浪费时间,但我完全相信日后你会感激你曾经的付出。
【考例4】Harry is feeling uncomfortable. He ______ too much at the party last night.
A. could drink
B. should drink
C. would have drunk
D. must have drunk
解析:D。
哈利感觉不舒服。昨晚的聚会上他肯定喝得不少。对过去发生事情的肯定推测,用must have done。
1. “情态动词can和could的否定式+比较级”表达最高级。
2. “can’t…+too+形容词或副词”或“can’t+形容词或副词+enough”表示“无论怎么……也不(过分)……”,“越……就越好”。
3. “may well+动词原形”意为“能,很可能”,相当于be very likely to。
4. “may as well + 动词原形”意为“最好,满可以,倒不如”,相当于had better。
5. “cannot but + do sth”表示“不得不,只好”。
【考例1】 I ______ myself more—it was a perfect day.
A. shouldn’t have enjoyed
B. needn’t have enjoyed
C. wouldn’t have enjoyed
D. couldn’t have enjoyed
解析:D。
我玩得再开心不过了,这真是完美的一天。此处couldn’t与比较级more搭配表达最高级的意义;couldn’t此处表推测“不可能”。
【考例2】No one ______ be more generous; he has a heart of gold.
A. could B. must C. dare D. need
解析:A。
没有人比他更慷慨大方了,他有一颗金子般的心。could表示推测(惊讶、怀疑、不相信的态度),用于疑问句、否定句和感叹句,而且本句中还包含了“否定词+比较级”表达最高级的一种用法,表示他是最慷慨大方的。
【考例3】I ______ thank you too much for all your help to my son while we were away from home.
A. won’t B. can’t C. can D. will
解析:B。
我再怎么感谢你对我儿子的帮助都不为过。“can’t…+too+形容词或副词”表达最高级。
【考例4】 Liza ______ well not want to go on thetrip — she hates traveling.
A. will B. can C. must D. may
解析:D。
丽萨不喜欢旅行,所以她很可能不旅行了。may well 和 might well意为“很可能”, 加强推测的语气,表示具有较大的可能性。
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