Question

一道GMAT语法题

Many teenagers undergo stress, but results of a recent study indicate that the patterns of stress that girls experienceare more likely to result in depression than are those that boys experience.
(A) are those that boys experience
(B) what boys experience
(C) boys' experience would
(D) boys' stress patterns do
(E) stress patterns of boys

正确答案为A 即原句正确 想问的是为什么those 前要加助动词are
答案上提示防止歧义 但是没看懂怎么歧义

Answer 1

原句大意----女生承受的压力模式 比 男生承受的压力模式 更有可能导致心情沮丧。

比较的双方是：the patterns of stress that girls experience 和 those that boys experience.
those= the patterns of stress （女生承受的压力模式 和 男生承受的压力模式）
are more likely 和 后面的 are 是对应的， 后面的are 省略了 likely to ……

如果没有 are ，
即“ are more likely to result in depression than those that boys experience. ”
从表面看，比较的双方有可能 是 depression 和 those that boys experience

（歧义-----导致 “depression ” 比起 导致“those that boys experience ”更有可能 ）

Answer 2

are those 指代的是results 所以用are . 而不是指代stress ,因为他是不可数名词。