Not "You wash the carrots." — say "Wash the carrots.". 命令句本身就是在对 you 说，主语可以省略。
试一试: ___ the carrots. (Wash / You wash / Washes) 答案: Wash — 命令句以动词原形开头。你在前面加了一个人，把它去掉：Wash the carrots，而不是“You wash”。
否定：Don't + 动词
要叫别人 不要 做某事，用 Don't + 动词原形。
Don't eat it yet!
Don't cut the bread.
Don't worry.
Not "Not eat it!" — say "Don't eat it!". 命令句变否定，动词前用 Don't，不能只用 'not'。
试一试: ___ the eggs yet. (Don't mix / Not mix / Don't to mix) 答案: Don't mix — 否定命令句是 Don't + 动词原形。不是 'Not mix'，Don't 后面也不加 'to'：Don't mix the eggs yet.
加 please 更礼貌
现在让命令句更柔和：在开头或结尾加 please。
Please wash your hands.
Cut the bread, please.
Please don't be late.
试一试: Make it polite: ___ wash your hands. (Please / You please / Please you) 答案: Please — 命令句从不以某个人开头，所以别加“you”：“You please”和“Please you”都不对。please 单独用就好：Please wash your hands。
Let's + 动词表示建议
想提议一起做某事时，用 Let's + 动词原形。
Let's cook dinner.
Let's wash the carrots.
Let's eat!
Not "Let's to cook." — say "Let's cook.". Let's 后面接动词原形，不加 to。
试一试: ___ make soup. (Let's / Let's to / Lets) 答案: Let's — 提议就是 Let's + 动词原形：Let's make soup。Let's 后面不加 'to'，而且 Let's 一定有撇号。
试一试: Tell your partner to mix the eggs: ___. (Mix the eggs / You mix the eggs / Mixes the eggs) 答案: Mix the eggs — 命令句就只是动词原形，前面不放任何人：Mix the eggs。（这是所有命令句的基础。）