祈使句表示请求、命令、建议、邀请等，谓语动词一律用原型，句子中通常不用主语，句末用惊叹好或者句号，用降调。
★肯定句：动词原型
Come here, please.
Go downstairs, please.
Stand up.
Sit down.
Be quiet.
Be careful.
祈使句中如果有唤语，一定要用逗号隔开，放在句首或者句尾：
Come in, Amy.
Sit down here, Tom.
Mary, give me a book please.
★否定：Don't+动词原型
Don't come here.
Don't sit down.
Don't stand up.
Don't give me it.
let sb. do 让某人做
Let me pass.
Let us have a rest.
Let's have a rest.
反意疑问：
Let's have a walk along the river, shall we?
Let us go out for a drink, will you?