It was in the dining hall _______ was locatedbehind the teaching building _______ I met her for the first time.

Which of the students _____ the examination? [ ]

The CDs are on sale！Buy one and you get ______completely free.

I think students should have mobile phones to call their parents at school..—_______. They often use them to play games instead.

The headmaster was dismissed three months ago.The post is too important to leave　　any longer,especially before the college entrance examination.