问题补充:
It is vital that every piece of equipment before the experiment.
A. is checked
B. will be checked
C. be checked
D. must be checked
答案:
A. is checked
B. will be checked
(答案→)C. be checked
D. must be checked
解析:本题考查虚拟语气。句型Itisvitalthat中,从句中谓语动词用should 加 动词原形,should通常可以省略。