相关知识
A large crowd（）expected at the football match。
来源：考试资料网2018-03-14
Economics, several courses of which I have taken thus far,（）to be difficult but useful for almost all students。
来源：考试资料网2018-03-14
The school staff（）gathered to hear the president speak。
来源：考试资料网2018-03-14
