大学英语四级考试：语法笔记讲义24

会计考友

　I don’t see how I could have done otherwise. 我看不出我当时还有别的做法。
+ O7 O/ R5 @6 ~: d% A　　Who could have supposed you were going to do such a thing? 谁会想到你会做出这样的事情。
　　Nobody could have foreseen such a calamity. 这样的灾祸谁也不会预想到。
8 m$ f  Z/ E. `$ {" {　　(2)could have done(但不是can)在肯定句中，表示“那时本来可以…;差点就要…”，有时用来进行婉转地批评(与might同意，但语气更强一些)：
9 S! A" e  ]- }/ h$ l1 l$ V  f- m' o　　We could have solved the problem in a more reasonable fashion. 这个问题我们本来是可以更合理得解决的。
4 k; b3 A* ?' p+ I- ~　　He could have told her, but he did not choose to. 他本来可以告诉她的，但他不愿这样做。
7 \/ P  a: t2 p% W0 d9 S　　When she heard the news, she could have cried. 听了这消息，她简直要哭出来了。
" p" ?# u3 y$ m　　I could have died laughing. 我简直要笑死了。
　　You could have been more considerate. 你其实可以想的更周到一些。
$ I' i5 ]/ t$ y: K　　We could have started a little earlier. 我们其实可以更早一些动身的。
& p4 |5 O" Q2 b+ C+ R2 Q7 v) i$ m　　The result could have been better. 结果本可以更好一些。
2 Z+ J) n2 b1 i　　5、should/ought to have done的含义。 “should/ought to have+过去分词”表示“过去应该做谋事却没有做”;“should not/ought not to have+过去分词”表示“做了不应该做的事”。含有责备或遗憾的意思。例如：
　　You shouldn’t /oughtn’t to have come here alone at such a late hour. 你这么晚的时候本不一该一个人来这里的。(实际是一个人来的)
0 X8 P3 f& e3 l+ F) Y- J　　She should/ought to have gone there alone. 她本该一个人去那里的。(实际上不是)
　　You should have come here ten minutes earlier. 你本应该早10分钟来才是。
+ n0 |6 i' \. C　　The boy shouldn’t have been playing the piano. 那孩子不应该一直在弹钢琴。
# P* g' ]2 n* R( q　　6、might, may, must表示推测时的区别: may，might, must可表示 推 测“可能”.根据表示可能性的大小，我们把这三个词排列为：might  
% T& T8 b. k1 x1 S8 P$ r　　It might rain tomorrow. (将来)明天可能下雨。
　　They might be watching TV now. (现在)他们可能正在看电视。
　　Jane might have visited the Summer Palace last year. (过去)去年珍妮可能去过颐和园。
　　He may have something important to do. (现在)他可能有更重要的事要做。
5 o8 Z: K, ~5 o/ _" z　　They may have been to Shanghai last summer. (过去)去年夏天他们可能去过上海。
6 {) s$ A* K$ C　　There must be something wrong with him. (现在)他肯定出问题了。
% e6 ~% e" S( V: J- H; u* k5 d　　He must have made a mistake. (过去)他一定是犯了个错误。
　　第四部分 几个用法的区别
! f: y5 @6 J  u6 R, |" d* [　　1、 can 和be able to的区别。can在表示“能力”时与be able to同义。但是can的时态形式不如be able to多。在一般将来时和现在完成时中只能用be able to。如：
; B6 B5 f3 u# F+ z　　She will be able to dance in a week. 她再过一星期就会跳舞了。
: g- G3 G7 K  n5 ^# i8 d6 z# e" H　　Nobody has ever been able to do it. 从来没有人能够做这事。
　　在过去时中，could表示具备某种能力，但不一定做事;而was able to表示努力设法去做谋事，成功后说明有能力，相当managed to do或succeeded in doing。这时，could和was able to是不能互换的。例如：
　　When he was a boy, he could swim across the river in fifteen minutes. 他小时侯，15分钟就能游过那河。(could表示能力，但不一定这么做)
　　He was able to swim across the river in fifteen minutes last week.
　　=He managed to swim across the river in fifteen minutes last week.
　　=He succeeded in swimming across the river in fifteen minutes last week.
8 `. V) l; y1 ^8 p: W　　上周他15分钟就游过了那河。(was able to表示真这样做了，而且成功了。这里不能用could)