根据句意或首字母填入所缺单词。

1.  As we know, a car has four w ______.

2. —Who's that w ______?

    —She's my mother.

3.  How many w______ teachers in your school?

4.  —Can I u  ______ your computer?

      —"Sorry, I'm u ______ it.

5.  We use milk to make c ______ .

燃烧室压力突然升高的现象、原因和处理措施。