B: They are used for...

Step 8　Roleplay (2d)

1. Read for the main idea of 2d.(略读，了解大意)

The main idea of 2d is about _______．

A. some small inventions 　　　　　B. a small invention-the zipper

C. a school project

[答案] B

2. Read for the specific ideas of 2d.(细读，把握关键信息点)

Read the conversation again and find out the answers to the following questions.

(1)Who invented the zipper？　(2)When was the zipper invented?

(3)When was it used widely?

[答案] (1)Whitcomb Judson. (2)In 1893. (3)Around 1917.

3. Read after the tape.

4. Read the conversation aloud in pairs.

5. Roleplay the conversation in pairs. Then go to the front of the classroom and perform it to the whole class.

Step 9　Language points(详见P212　课堂互动探究)

be used for, be invented by...

课堂小结

1. 一般过去时的被动语态表示主语是过去某个动作的承受者，谓语动词由"was/were＋动词的过去分词"构成。

2. 把主动语态中的主语放在介词by之后作宾语，将主格改为宾格("by＋人称代词"短语可以省略)。