Question

帮忙解释几道英语题，谢谢啦！O(∩_∩)O~

1-.It must have been hard word.
-Yes,it_____Dr.Yuan more than 20 years to develop the super hybrid rice.
A.takes B.has taken C.was taking D.took
答案：D
2.--Did you go to Mrs.Smith's birthday party?
--Of course.Every boy and every girl in our class______.
A.has been invited B.have been invited C.was invited D.were invited
答案：A

Answer 1

1 it takes sb sometime/sth. to do sth. 做某事花费某人……it 做的是形式主语。
2. every +名词单数+every +名词单数做主语时，谓语动词用单数。我们班里的每个男孩和女孩都已经被邀请。

Answer 2

就是这样的 没有错 固定的搭配与句型结构

追问

第二题为什么不选C呢

Answer 3

对