请教OG158的一个小问题

The word or phrase that begins this sentence should establish the contrast between the size of the United States population and the activities of its citizens. Choices D and E are the only ones that establish the contrast, and only E, the best choice, expresses meaning accurately with the phrase Although accounting for. With in choice A and Despite having in choice D confusingly suggest that United States citizens somehow possess, rather than constitute, 5 percent of the world's population. Choices B and C lose the contrast between the opening phrase and the main clause, and As is unidiomatic in B.

不明白OG得这句解释，AS固然没有表达这种转折对比，但as 表作为讲，也不是不通阿（当然撇开contrast不谈）

作为世界上5%的人口，美国人。。。

我认为，as放在句前表“作为”的时候，前后的名词应该是同质的，比如：

As a teacher, I can give you some advice.

这里teacher和I都是人。

但是上面这题，5 percent和citizen就不是同质的，所以as在这里作为用的话，不正确！

请NN指教！

mmmzzz:

你自己已经是nn啦，不用指教啦

可我觉得前后应该是5 percent of the world's population 和citizen啊

但是这句5 percent of the world's population 中心词是5 percent亚