【解析】
祈使句的否定形式,是由谓语动词前加do+not构成.
【参考答案】
1.Please listen to the teacher
Please don't listen to the teacher.
2.Mary,halp me,please
Mary,don't help me,please.
3.Please do your homework now,Linda.
Please don't do your homework now,Linda.
4.Wash your hands first please,Dennis.
Don't wash your hands first please,Dennis.
5.Let him go out
Don't let him go out