Ⅰ. Introduction
1. Do exercise 1 on page21
2. Translate the words and phrases into Chinese.
（1）一道闪电 （2）经历一场洪灾
（3）指的是，查阅 （4）灾难
（5）飓风 （6）龙卷风
Ⅱ. Reading and vocabulary
1. Do exercise 2 on page 22
2. Answer the following questions.
（1）Which of the following descriptions about tornado is not correct?
