问题
选择题
One of the requirements for a fire is that the material _________ to its burning temperature.
A．is heated
B．be heated
C．would be heated
D．shall be heated
答案
答案：B
题目分析：句意：对火的要求之一是材料要被加热到燃点。主语是requirement，suggestion，order，advice等词后面的表语从句中用虚拟语气：should do，should可以省略，而且material和heat是被动关系，用被动语态，选B。