根据句意和首字母填写单词。

1. When was the c_____ invented?

2. I usually wear s_____ when I am at home.

3. Please put the used b_____ into the box.

4. What do you think is the most useful i_____?

5. Here are the shoes with a_____ heels.

攻丝时的挤压作用，使攻出的小径大于原底孔直径。