单项选择题

It is required that such insulator (绝热体) ______ a heat resistant material.

A．must be made of
B．should be made of
C．will be made of
D．would be made of

<上一题目录下一题>

热门试题

单项选择题The paint is still wet, ______!

单项选择题Jenny didn't have time to go to concert last night because she was busy ______ for her examination.