熔断器的选择有：一是（），二是（）。
参考答案：熔体的选择；熔管的选择
用所给单词的适当形式填空
1. It's great _____(visit) the Great Wall.
2. Are you looking forward to _____(watch) the football match?
3. Chinese people are very _____(friend).
4. Bill wants to be a _____(science) when he grows up.
5. I have lots of things _____(do) this Sunday.
在DOS系统中，下列文件名中非法的是( )。
A．(ABCDEFG1
B．(ABCDEFG1.234
C．(ABCD_EFG
D．(ABCD\EFG
