求教og一语法题！！

michaelmay17

41.    Since chromosome damage may be caused by viral infections, medical x-rays, and exposure to sunlight, it is important that the chromosomes of a population to be tested for chemically induced damage be compared with those of a control population.
(A) to be tested for chemically induced damage be compared with
(B) being tested for damage induced chemically are compared with
(C) being tested for chemically induced damage should be compared to
(D) being tested for chemically induced damage are to be compared to
(E) that is to be tested for chemically induced damage are to be comparable with
答案选A问题是这里为什么要用虚拟语气？

12604698

这里的虚拟是
it is good /important/necessary +that 从句 。从句用虚拟语气。

michaelmay17

恩，了解了，谢啦~