关于to do sth is to do sth的一个疑惑。OG10 th-Q84

venus2elva

84.One legacy of Madison Avenue’s recent campaign to appeal to people fifty years old and over is the realization that as a person ages, their concerns change as well.

(A) the realization that as a person ages, their

     (B) the realization that as people age, their

(C) to realize that when a person ages, his or her

(D) to realize that when people age, their（B）

(E) realizing that as people age, their

想请问这里为什么不用to do sth is to do sth 的形式？ 这个形式的使用有什么特殊的要求?
多谢指教。

TracyWei

恩，我来回答一下，我也提了问，但是没人回答，挺惨的！

这个你得看句子意思，这句话仅仅是介绍这个LEGACY的内容，因此不用这个结构

venus2elva

多谢。