166.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
2.what引导的名词性从句做主语时，主句谓语动词的单复数情况：
(1)What在从句中做主语，主句谓语由what从句的谓语决定。
What is difficult to understand is A.
What are difficult to understand areA and B.
(2)what在从句中做宾语，主句谓语由主句表语/宾语决定what they want are XX,XX&XX。
What his father left him are a few English books.
也就是说，what引导主语从句，主句的主谓一致，不一定要用is，而是what后面用啥主句就用啥: what is... is... /what are...are...
而what从句中的主谓一致，位于的单复数则需要根据主句动词后面名词单复数来决定
所以，结合以上两点才会有 What are difficult to understand areA and B
在第二条规则里的后两个例子中，what they want are A, B, and C. what his father left him are ...books. 个人感觉应该是倒装，把宾语提前了作者: running2k 时间: 2012-12-3 06:55
