can开头疑问句

mustn't表示语气非常强烈的禁令.绝不可以的意思

1、在回答must开头的一般疑问句时,肯定回答用must,否定回答用needn't或don't have to.如：

1)—Must I finish my homework before eight o'clock?

—Yes,you must.

2)—Must I attend the meeting?

—No,you needn't(No,you don't have to).You can ask Tom to go instead.

2、在回答may开头的一般疑问句时,肯定回答用may,否定回答用mustn't.如：

1)—May I watch TV after supper?

—Yes,you may./ No,you mustn't.

2)—May I stop here?

—No,you mustn't.

3、在回答need开头的一般疑问句时,肯定回答用must,否定回答用needn't.如：

1)—Need we stay behind after school?

—Yes,you must.

2) —Need he go now?

—No,he needn't.

MUST 做情态动词的否定形式

就是needn't或can't ,couldn't等

但绝对不是mustn't

这个可以说是约定俗成的,只有这个用法,记住就是了

1) 表示必须、必要.

You must come in time.

在回答引出的问句时,如果是否定的,不能用mustn’t（禁止,不准）,而用needn’t, don’t have to（不必）.

---- Must we hand in our exercise books today?

---- Yes, you must.

---- No, you don’t have to / you needn’t.

2) must是说话人的主观看法, 而have to则强调客观需要.Must只有一般现在时, have to 有更多的时态形式.

1． he play isn’t interesting, I really must go now.

2． I had to work when I was your age.

3) 表示推测、可能性（只用于肯定的陈述句）

1． You’re Tom’s good friend, so you must know what he likes best.

2． Your mother must be waiting for you now.

以must 引出的一般疑问句,其否定回答通常是用 needn't（=don't have to）,这与其说是一个语法问题,不如说是一个语境或上下文是否通顺的问题.

注意以下各组问答句,并注意体会其汉语译文：

—Yes,you must．是的,必须天亮前来.

—No,you needn't．不必天亮前就来.

—No,you don't have to．不必天亮前就来.

—Yes,you may．当然可以.

—Of course you may[can]．当然可以.

—No,you may not[mustn't,can't]．不行.（语气较生硬）

—You'd better not[Better not]．最好不要抽.

—I'd rather you didn't．还是不抽的好.

—Please don't．请不要抽.

—Yes,you must[have to,should]．是的,今天必须完成它.（肯定回答不能用Yes,you need,因为情态动词need 只用于否定句或疑问句,不用于肯定句）

—No,you needn't．不必今天就完成它.

—No,you don't have to．不必今天就完成它.

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