what引导的从句的谓语的单复数怎么决定？

谢谢mm的解答！

如果不是be动词作谓语，而是happen、make等作谓语呢？

谢谢mm！

也就是说如果我能从句子的其他部分判断出what指代的是复数名词，就要用复数谓语。

agree with LES

不过偶觉得这种题最好的判断是还原法，既看句子的真正主语是什么。

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

应用上面的理论,无法理解答案为什么是B不是A,the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals.三个并列做主语,很显然主语用复数啊,NN们解答一下,看了一个小时,越看越糊涂.

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。

这是笨蛋语法上的话,我是不是可以这样理解,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这个优先于主句的谓语动词形式由后面的名词决定,如果不时这么理解的话,我觉得答案应该是what ARE much more difficult to determine are才对,我都绕晕了,HELP!!!

a noun clause subject takes a singular verb:

what they should do is obvious.

WHAT是个例外,一般的名词性从句后面是跟单数