语法专讲之情态动词
一、综述
情态动词有一定到意义，但不能独立作谓语，往往和后面到动词原形一起构成谓语部分。
二、分类
一）can, can’t
could, couldn’t
be able to
二）should, shouldn’t;
must, mustn’t;
have to, don’t have to;
ought to, ought not to
三）need, needn’t;
dare; dare not
shall; shan’t
will, would
四）情态动词+ 完成时
三、高考试题引入：
1. —Do you know where David is? I couldn’t find him anywhere.
—Well，he have gone far—his coat’s still here.
A. shouldn’t
B. mustn’t
C. can’t
D. wouldn’t
2. My MP4 player isn’t in my bag. Where I have put it?
A. can
B. must
C. should
D. would
3. —She looks very happy. She have passed the exam. —I guess so. It’s not difficult after all.
A. should
B. could
C. must
D. might
4. Helen go on the trip with us，but she isn’t quite sure yet.
A. shall
B. must
C. may
D. Can
四、情态动词详细归纳：
一）can、could与be able to
1. 表示能力
e.g. Most of us can use the computer now, but I couldn’t use it last year.
e.g. He was not able to climb up on the top of the mountain.
e.g. He was able to go to the party yesterday evening
in spite of the heavy rain.
2. 表示客观的可能性
e.g. Sometimes the temperature in Wuhan can fall to ten degrees below freezing.
e.g. It can be quite windy in Wuhan, especially in spring.
3. 表示推测。多用于否定句和疑问句中。
e.g. He can’t be our head teacher as he has gone to Shanghai for a meeting.
对比：
e.g. He may not our head teacher as he said he has gone to Zhengzhou for a meeting.
总结：can’t 不可能（语气最肯定）；
well may not 很可能不（语气比较肯定）；
may not可能不（语气最不肯定）
4. 表示惊异或怀疑，常用语疑问语气。
e.g. 那怎么会是真的呢？
How can it be true？
e.g. 这到底是什么意思？
What on earth can this mean?
5. 表示请求，常用could 语气更委婉。
e.g. ---Can I go now?
--- Yes, you can. / No, you can’t.
e.g. --- Could I come to see you tomorrow?
--- Yes, you can. ( No, I’m afraid not. )
e.g. Could you wait a few days for the money?
e.g. Could you be here at eight o’clock tomorrow morning?
6. 在将来时和完成时中只能用be able to
e.g. 我确信我很快就能得到那份工作。
I am sure I will be able to get this job soon.
e.g. 他们已经能够按时完成任务了。
They have been able to finish the work on time.
7. 表示经过努力而成功地办到某事，用be able to，这里be
able to 相当于：succeed in 或manage to
e.g. 经过几年的努力，他终于通过了考试。
After years of hard work he was able to pass the final exam.
8. can’t wait表示“急于做某事”相当于be eager to ----
e.g. I can’t wait to read this story book.
我非常渴望读这本故事书。
e.g. I couldn’t wait to see her.
我渴望见到她。
9. can not ---- too----表示“再----也不为过”；“越---- 越
