When the technique known as gene-splicing was invented in the early 1970's, it was feared that scien­tists might inadvertently create an "Andromeda strain," a microbe never before seen on Earth that might escape from the laboratory and it would kill vast numbers of humans who would have no natural defenses against it.

(A) it would kill vast numbers of humans who would have no natural defenses against it

(B) it might kill vast numbers of humans with no natural defenses against it

(C) kill vast numbers of humans who would have no natural defenses against it(虚拟语气没有错)

(D) kill vast numbers of humans who have no natu­ral defenses against them

(E) kill vast numbers of humans with no natural defenses against them

解释中的最后一句话In addition, choices B, D, and E lack would and thus do not express the conditional

问题一：不是有一个表示虚拟的might动词了吗？再按照解释所说的加上would不就重复了。

问题二：就D来在WHO后面加上would作为虚拟动词表示条件，但是用would表示条件或者含蓄条件时，都是用在主句上的，例如if v-ed, …would v.句型，it would be pity to miss the play（如果错过了这场戏，将是非常遗憾的），大家有看过表示虚拟的动词用在丛句中吗？

1. 这个would是在以who引导的从句里的. 主句与从句怎么可以共用一个虚拟语

气词.

2. 用在从句中的太多了. If I were you, I wouldn't have let her go.

虚拟可以主从句都用的啊，这点我很确定的。