用括号里所给单词的正确形式填空。

1. Those toys_____(make) of plastic.

2. There were a lot of great_____(invent) in the 20th century.

3. We should make up our mind to improve our listening, speaking, Reading and Writing _____(able).

4. There's but one China and Tai wan is _____(part) China.

5. _____ it was so cold ,he went out without an overcoat.

三相异步电动机的（）中不进行外部通电，靠感应产生电流。