问题

I think this is ___ useful book, so I will keep it for ever.
A:a
B:an
C:/
D:the
B:an
C:/
D:the
正确答案是:
同类题型
There are classrooms on the ground floor. One of them is ours.
My classmate Wang Yong always comes up special solutions ____ our math problems.[ ]
___ is no good ___ without doing anything.
While I ___________ TV, the bell rang.
Please don’t talk loudly here. The students _________the teacher in class.