Prep sc

kun861010

The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleoithic peoples has been established by carbon dating, but what is much more difficult to determine are the use to which primitive ppeoples put the caves, the reason for their decoration, and the meaning of the magnificently depicted animals.
d,has been established by carbon dating, but what is mucch more difficult to determine is
答案是d，但是我选了a。我想问为什么后面是is呢？后面明明是3个方面，不是应该用are吗？我想问什么时候动词是跟动词后面的宾语一致，什么时候是和前面的一致呢？麻烦了，谢谢

biantaishabi

动词应该是随主语来变化的.
这里的主语是what is much more difficult to determine， what从句里面用的是单数is， 后面这个从句的谓语也应该是单数

主语一般都在谓语前面， 不过有时候在倒装句里面主语会到后面，比如在湖上有四个鸭子。 On the lake are four ducks.

果汁软糖

ls正解 谓语应该是和主语保持一致的 有时候倒装要注意谓语在前主语在后，但是还是要和主语保持一致