—Excuse me, Maria. Can I use your bike?
—Sure. Here you are. But you must return it _____ time.
| A．in | B．at | C．on | D．to |
---It was ___________ who helped us out of danger.
---What brave and helpful children! We should learn from them.
| A．they | B．them | C．their | D．theirs |
My mother was doing the cleaning in the sitting room ________ the telephone rang.
| A．when | B．while | C．since | D．as soon as |
Every day, too much water _______ in our school. We should save it.
| A．is wasted | B．wastes |
| C．was wasted | D．wasted |
— Must we go to see a doctor at once when we have the flu?
—No,_____.
A. we mustn’t
B. we shouldn’t
C. we don’t have to
— ____ you _______your book to the library? — Yes. I returned it yesterday.
A. Did, return
B. Have, returned
C. Will, return