三、must, have to的用法
1. 两词都是“必须”的意思，have to 表示客观的需要，must 表示说话人主观上的看法，即主观上的必要。
如：My brother was very ill, so I had to call the doctor in the middle of the night.
我弟弟病得很厉害，我只得半夜里把医生请来。(客观上需要做这件事)
He said that they must work hard. 他说他们必须努力工作。（主观上要做这件事）
2. have to有人称、数、时态的变化，而must只有一种形式。
如：He had to look after his sister at home yesterday. 昨天他不得不在家照看妹妹。
3. 在否定结构中：don't have to 表示“不必”
mustn't 表示“禁止”，
如：You don't have to tell him about it. 你不一定要把此事告诉他。
You mustn't tell him about it. 你一定不要把这件事告诉他。
—Must I finish the homework right now?
我现在必须完成家庭作业吗？
—Yes, you must. / Yes, you have to. 是的。
(—No, you needn’t. / No, you don’t have to. 不，不必。)
4. must be 表语，表示推测，它的否定和疑问形式用can代替must。
如：This must be your pen. 这个一定是你的钢笔。
四、should的用法
（1）用来提供帮助、提出建议，要求对方给出意见。
如：Should I help you with the community affairs? 我可以帮你做一些社区事务吗？
Should we clean the classroom now? 现在我们可以打扫教室吗？
（2）表达义务、职责等。
如：I think today’s children should really learn to respect their elders.
我认为今天的孩子应该好好学习尊敬长辈。
You should （= ought to ） tell your mother about it at once. 你应该立即把此事告诉你妈妈。
He should work harder. 他应该更加努力。
You should help your mother with the housework. 你应该帮你母亲做家务。
例. Look out! The knife is very sharp. You ______ cut your finger.
A. need B. must C. should D. may
五、will, would的用法
1. 表示“将、将要、自愿做…”等。
如：People will die without air or water. 人离开水和空气将会死的。
I will do my best. 我将会尽力而为。
2. would like； Would like to do = want to 想要，为固定搭配。
如：Would you like to go with me? 你想和我一起走吗？
3. Will you…? Would you like…? 表示肯定含义的请求劝说时，疑问句中一般用some, 而不是any。
如：Would you like some cake? 你想要一些蛋糕吗？
Exercise 5
1. ______ I know your name?
A. May B. Will C. Shall D. Must
2. What kinds of homes will we live in the future? Nobody ______ be sure, but scientists are working out new ideas now.
A. will B. may C. can D. must
六、had better的用法
表示“最好”，相当于一个助动词，只有一种形式，后面要跟动词原形，否定词形式为had better not。
如：It is pretty cold. You’d better put on my coat. 天很冷，你最好把我的大衣穿上。
You had better go now你最好现在就走
He'd(=He had) better do it now他最好现在做
She'd better not cry她最好别哭
例. You ____ your tooth pulled out before it rot completely.
A. had better got
B. had to get better
C. had better to get
D. had better get
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