用所给词的适当形式填空

1. Look! Whose ________ (Walkman) are these? Perhaps they are the twin's.

2. Is there an ________ (electric) shop in your town?

3. Amy wants to buy some presents for ________ (they).

4. Do you understand the ________(mean) of the new world?

5. Do you like to have cold ________ (drink)?  

6.We usually go ________ ( shop )on Sundays.

7. Listen !Someone ________ ( knock )at the door.

实验室中常用测定蛋白质相对分子质量的方法有______、______和______等。