B. Stop when the light is red.

C. Turn right.

D. Don't park here.

E. Be careful!

F. Don't play on the street.

祈使句表示请求、命令、建议，句子通常不带主语，谓语动词用原形。肯定形式一般以动词原形开头，其否定形式是在谓语动词前加do not或don’t。

祈使句