求助gwd17-38，已经搜索过的

38. GWD17-Q38:

All Y chromosomes in existence today are descended from a single ancestor’s who is thought to have lived about 140,000 years ago.

1. a single ancestor’s who is thought to have lived
2. a single ancestor’s who was thought to live
3. a single ancestor whom it is thought had lived
4. the Y chromosome of a single ancestor who is thought to have lived
5. the Y chromosome of a single ancestor whom it was thought had lived

还没搞清楚为什么不选b，总觉得d用完成时不好吧

请nn解惑

选D没问题,用所有格形式不如直接用名词形式好,这个事情一直持续到现在,用现在完成时合适.

额，我和楼主同问，为虾米米回答。

我瞎琢磨着，可能是他已经死了，动作也结束了……自己乱讲什么东西

反正其它的都不对，排除

给这样一个信息 大家应该就能明白为什么选D了吧...

【每个男人身体中的Y染色体只有一条】 而a single ancestor’s是a single ancestor’s chromosomes...这怎么对捏？^^

当然，我觉得这貌似考得有点儿偏了 我是文科生 当时也就是凭感觉做对了....这都是问了理科生朋友才知道的...