菜鸟OG211

211. The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleolithic people has been established by carbon-14 dating, but what is much more difficult to determine are the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals.

(A)  has been established by carbon-14 dating, but what is much more difficult to determine are

(B)  has been established by carbon-14 dating, but what is much more difficult to determine is

(C)  have been established by carbon-14 dating, but what is much more difficult to determine is

(D)  have been established by carbon-14 dating, but what is much more difficult to determine are

(E)   are established by carbon-14 dating, but that which is much more difficult to determine is

Two instances of subject-verb agreement must be observed in this sentence: The period ... has been established and what is much more difficult to determine ... is. Both clauses have singular subjects and must have singular verbs. Only B, the best choice, observes these requirements. A incorrectly uses the plural form are in the second clause. Choices C and D incorrectly use the plural form have in the first clause, and D incorrectly uses are in the second clause as well. E incorrectly uses the plural form are in the first clause. Furthermore, because the date of the period in question was established before the writing of the sentence, the verb of that clause must be in the present perfect form (has been established).

知识点——主谓一致：what 从句做主语时，主句的谓语动词形式由后面的名词决定；如果what在what从句中做主语，它的谓语动词形式应该与主句的谓语动词形式保持一致。/主语从句做主语只有这个例外，其他的都用单数谓语。

最后的主谓一致说what 在what从句中做主语, 以及后面的话是啥意思啊,能否举例说明啊,多谢啊

这句话的意思是，period可以通过carbon-14来决定。但是更难决定的东东是the reason ，the use ，and the meaning 。三个并列。

不知道MM要什么举例？

欢迎讨论

og30.   What was as remarkable as the development of the compact disc has been the use of the new technology to revitalize, in better sound than was ever before possible, some of the classic recorded performances of the pre-LP era.

(A) What was as remarkable as the development of the compact disc

(B) The thing that was as remarkable as developing the compact disc

(C) No less remarkable than the development of the compact disc

(D) Developing the compact disc has been none the less remarkable than

(E) Development of the compact disc has been no less remarkable as

是要找到平行的例子么？

本来是想问如果what在what从句中做主语，它的谓语动词形式应该与主句的谓语动词形式保持一致。

不过看到叶子JJ的回答已经知道啥意思了. 就是was 和 has 是要保持一致的,对吧