用所给单词的适当形式填空。

1. Listen! They______(sing)in the classroom.

2. 一Where's Bill?

      一He_______(take)photos over there.

3. He_______(not watch)TV now.

4. It's six o'clock in the evening. She______(eat)dinner .

5. Look! The students_________ (wait) for the school bus.

甲在乙处加工西服两套，取回西服时因钱不够，未能付清加工费，乙只允许甲取走其中一套，称另一套等到甲将钱交清之后再取，乙对此套西服的占有基于()。

A．抵押

B．质权

C．留置权

D．所有权