It‘s important to listen to the teacher.（改为祈使句）
Listen to the teacher.
Please sit next to Nancy.（改为否定句）
Don't sit next to Nancy.
The teachers often tell the students to be careful.（改为祈使句）
Tell the students to be careful.
lt’s rude to talk with your classmates in that way.（改为否定句）
It isn't rude to talk with your classmates in that way.
Don‘t bring your dog here.（改为肯定句）
Bring your dog here.