Since chromosome damage may be caused by viral infections , medical x-ray, and exposure to sunlight , it is important that the chromosome 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
能解释下为什么是A吗?
这里应该是虚拟.
记得tonyadidas说过it is important that 是可以有虚拟的用法出现的,在OG上有体现
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