根据句意及首字母的提示，补全单词。

1. I was waiting for the school bus but it didn't come. Then I r     _    it was Saturday.

2. Have you ever forgotten a r    _      birthday?

3. Tom was e      _   because he had stayed up all night working.

4. Don't forget to l     _    the door when you go out.

5. I will go to the c    _     party tonight. Would you like to go with me?

锅炉过热器的材料大多采用一些含有( )的、具有良好高温强度、能耐热的合金钢制造。

A．镍

B．铬

C．钼

D．钒