181. Because of the enormous research and development expenditures required to survive in the electronics industry, an industry marked by rapid innovation and volatile demand, such firms tend to be very large.

(A) to survive

(B) of firms to survive

(C) for surviving

(D) for survival（B）

(E) for firms’ survival

the answer is B, but I think E is better. who can tell me the reason? thanks!

181. Because of the enormous research and development expenditures required to survive in the electronics industry, an industry marked by rapid innovation and volatile demand, such firms tend to be very large.

注意后面有一个such firms，那么前面应该有一个很明确的名词firms，而E却把firms变成了firms'所有格形式，这样后面无法指代前面这个了。

注：'s的所有格形式中的修饰语是无法被后面代词指代的；n+of + n则可以。

请解释一下好吗,为什么做修饰语就不能被指代了

上面的话说的太effectievness了!

让我忽然想到了"上方宝剑", 什么东西只要是ETS说的, 基本大家就只有记的份了.

看来我还要慢慢适应ETS的思维呀!!!