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 |