Question

We are happy to have our () holiday,because seven days () a long time to have a picnic.

1.We are happy to have our () holiday,because seven days () a long time to have a picnic.
A.seven-days;is B.seven-day;is C.seven-day;are D.seven-day's;are
我认为是C，但答案是B，不知为什么
2.I wabder if I can ask him () time.
A.four B.fourth C.the fourth D.a fourth
我认为是C，但答案选D，不知为什么
以上题目请说明理由，谢谢！~

Answer 1

1. B.
解释：英语语法中规定，如果是时间/金钱/重量/距离等做句子主语时，其视为一个整体，谓语动词必须用单数形式。
再如：Ten years is a long time.

2. D
解释：the fourth time不能单独做状语，必须改成for the fourth time“第四次”；
而a fourth time意思是“又一次/再一次”，可以单独做状语。