求教GMAT Prep的一道语法题

The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleolithic peoples has been established by carbon dating, but what is much more difficult to determine are the use to which primitive peoples put the caves, the reason for their decoration, and the meaning of the magnificently depicted animals.

A. has been established by carbon dating, but what is much more difficult to determine are

B. have been established by carbon dating, but what is much more difficult to determine are

C. have been established by carbon dating, but that which is much more difficult to determine is

D. has been established by carbon dating, but what is much more difficult to determine is

E. are established by carbon dating, but that which is much more difficult to determine is

这个题选C

但是what is more dfficult to determine is 后面加一连串and，is用的对吗？

这是GMAT Prep上的题目 我从CD上下的破解版

我也选A

呵呵

没错，这个题选D。

has been 的主语是period，所以单数。

what引导的从句作主语，谓语也是单数。

实在不好意思 我最近犯了两个这种错误了 大脑有点短路

答案是D

我想问的是what is more dfficult to determine is 后面加一连串and，is用的对吗？

这个is 应与 what is more difficult to determine 这个主语从句的谓语动词，也就是<what is more...>中的 is一致，所以此处应用单数形式的谓语形式is ,而不是 are.不用看后面~