【往期回顾】
接下来，我们就来看看第63课的“每课一句”。
Lesson 63 Thank you , doctor.
How's Jimmy today?
He's better, thank you, doctor.
Can I see him please, Mrs. Williams?
Certainly, doctor. Come upstairs.
You look very well, Jimmy. You are better now, but you mustn't get up yet. You must stay in bed for another two days.
The boy mustn't go to school yet, Mrs. Williams. And he mustn't eat rich food.
Does he have a temperature, doctor?
No, he doesn’t.
Must he stay in bed?
Yes. He must remain in bed for another two days. He can get up for about two hours each day, but you must keep the room warm.
Where's Mr. Williams this evening?
He's in bed, doctor.
Can you see him, please? He has a bad cold, too!
——选自《新概念英语》第一册，外语教学与研究出版社，1997年10月第1版
本课侧重学习的是情态动词must的用法。
其实，在第61课中已经出现了must的用法，只是在第61课里侧重学习的是must的肯定句的用法，比如第61课中有这么两句话：
We must call the doctor.
He has a bad cold, Mrs. Williams, so he must stay in bed for a week.
由此可以看出，must的肯定句的用法为：
sb. must do sth.
到了本课第63课里，主要学习must的否定句和疑问句的用法，比如本课里出现的这几句话：
..., but you mustn't get up yet.
The boy mustn't go to school yet, Mrs. Williams. And he mustn't eat rich food.
- Must he stay in bed? - Yes.
需要注意的是：
must表“必须”时的否定形式并不是mustn't，而是needn't（到了下半册，还会学习其他否定表达方式）。
needn't表“不必”，而mustn't表“不能；禁止”。
因为must是情态动词，所以变成一般疑问句时，只要把must提到句首即可，但要注意其否定回答时要用needn't。比如：
- Must he stay in bed?
- Yes, he must.
- No, he needn't.
【注意】
除了情态动词must以外，在第61和63课里也出现了情态动词can的用法。
只是在第61课里的can表“能；会”，是一种能力。其基本用法是：
sb. can do sth.
如：
He can drive a car.
其否定表达为：
sb. cannot/can't do sth.
如：
He cannot/can't drive a car.
其一般疑问句为：
- Can sb. do sth.?
- Yes, sb. can.
- No, sb. can't.
如：
- Can he drive a car?
- Yes, he can.
- No, he can't.
当然，句子的主语也可以是sth.，如：
The dog can run very fast.
此外，要注意can的否定表达cannot，在书写上can和not不能分开写。
在第63课里的can表“可以”，是一种许可。其用法与can表能力是类似的，其基本用法是：
sb. can do sth.
如：
I can give you some help.
其否定表达为：
sb. cannot/can't do sth.
如：
I cannot/can't give you any help.
其一般疑问句为：
- Can sb. do sth.?
- Yes, sb. can.
- No, sb. can't.
如：
- Can you give me any help?
- Yes, I can.
- No, I can't.
只是，与can表能力时不同的是，当can表允许时，其主语一般都是人。
本课出现了系动词remain、stay和keep，它们被称作持续系动词，主要用来表示状态的持续。持续系动词后面可接形容词、名词或短语。如：
It remains a mystery (谜团) for a long time.
Keep quiet, please.
You must stay in bed for a week.
有关前面学过的感官系动词的用法，可参考下面的链接：
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