情态动词must表示推测（非常重要）

[微风][烟花]情态动词must可以表示推测，但不能用于否定句中。后面有4个思考题，建议完成。

一，对现在的推测

1.Mary must be ill.

玛丽一定生病了。

2.My brother must be in the room.

我弟弟一定在房间里。

二，对过去的推测must have done

1.The boy must have learned to play the piano for at least two years.

那个男孩一定学过钢琴两年多。

2.My mother must have come here.我妈妈一定来过。

三，推测的反意疑问句

变成反意疑问句的时候，一定要把句子还原成不推测的句子，然后再变成反意疑问句。

1.Mary must be ill, isn't she?

玛丽一定是生病了，对吗？

2.My mother must have come, didn't she?

我妈妈一定来过这里，是吗？

四，否定句用can't

1.Mary can't be ill.

玛丽不可能生病了。

2.My mother can't have come here.

我妈妈不可能来过这里。

五，思考题[微风][烟花]

1.The boy must have learned English for five years, _ _?

2.You must be cooking at nine o'clock last night, _ _?

3.Lucy must have phoned me, _ _?

4.They can't have been here for so long a time, _ _?