Step Ⅰ.Revision

1. 全班听写，复习 must 和 mustn’t。1）DO eye exercises.

We must do eye exercises every day.

1. Don’t look outside the window.

We mustn’t look outside the window.

1. Look at the blackboard.

We must look at the blackboard.

1. Don’t open your books.

We mustn’t open our books.

1. 通过师生问答，复习 when 和 if 引导的状语从句。T：When the bell ring⋯

S1：I must go into the classroom when the bell rings. T：When you cross the road⋯

S2：When I cross the road，I must look carefully. T：If it rains tomorrow⋯

S3：If it rains tomorrow，I’ll stay at home. T：If the traffic lights are green⋯

S4：We must stop and wait if the traffic lights are green.