prep 1-123

123.
                (30997-!-item-!-188;#058&004357)

According to two teams of paleontologists, recent fossil discoveries in Pakistan show that whales, porpoises, and dolphins are more closely related to some of the oldest known even-toed ungulates--a group of hoofed mammals that today includes cows, camels, pigs, and hippos--than to any other mammals.

(A) that whales, porpoises, and dolphins are more closely related to some of the oldest known even-toed ungulates--a group of hoofed mammals that today includes cows, camels, pigs, and hippos--than

(B) that whales, porpoises, and dolphins are more closely related to some of the oldest known even-toed ungulates--a group of hoofed mammals that today include cows, camels, pigs, and hippos--as

(C) whales, porpoises, and dolphins to be more closely related to some of the oldest known even-toed ungulates--a group of hoofed mammals that today include cows, camels, pigs, and hippos--than they are

(D) whales, porpoises, and dolphins as being more closely related to some of the oldest known even-toed ungulates--a group of hoofed mammals that today includes cows, camels, pigs, and hippos--as they are

(E) whales, porpoises, and dolphins as more closely related to some of the oldest known even-toed ungulates--a group of hoofed mammals that today include cows, camels, pigs, and hippos--than

答案是A，为什么includes用单数呢？先行词应该是mammals吧，再不济a group of hoofed mammals也应该是复数亚？

我觉得在这里不是A of B的结构

a group of就是一个固定搭配,谓语动词用单数

A of B的结构中谓语动词到底用什么,必须要看句子的逻辑意思,不能一概而论

a group of 可以用单数，也可以用复数吧

LDC例句：A group of us are going to London.

所以我的理解是：只能说includes用在这里没错，不能说一定要用单数或复数