帮忙看看两道语法题

新东方语法教程

Exercise 26

30.of all the art-related reference and research library in North American,that of the Metropolitan Museum of a Art in New York city is among the longest and most complete.

答案是B,是不是把that of 去掉??

Exercise27

25.Unique among bivalves,scallops swim extremely well.propelled by jets of water expelled while snappped the shell shut.

答案是C,为什么?

1.我觉得是A错， 改成libraries

2. snapped-->snapping,

Exercise 26的30题：怎么对的答案？应该是A。

啊?对哦,不好意思,对错答案了.怪不得觉得怪怪的.