13.1 祈使句结构

13.1 祈使句结构
       
　 祈使句用以表达命令，要求，请求，劝告等。

1） 祈使句有两种类型，一种是以动词原形开头，在动词原形之前加do (但只限于省略第二人称主语的句子)。
　　　 Take this seat.
　　　 Do be careful.
　否定结构：
　　　Don't move.
　　　Don't be late.

2） 第二种祈使句以let开头。
　　Let 的反意疑问句
　a. Let's 包括说话者　
　　 Let's have another try，shall we / shan't we?
　 = Shall we have another try?

　b.　Let us 不包括说话者
　　 Let us have another try，will you / won't you?
　 = Will you please let us have another try?

否定结构：
　Let's not talk of that matter.
　Let us not talk of that matter.