Air pollution, together with littering, ____ many problems in our large industrial cities today.
| A．causes | B．cause | C．caused | D．causing |
Mary is one of the brightest students who_________ from New York University.
| A．is graduated | B．have graduated |
| C．has graduated | D．are graduated |
Mr. Alcott, headmaster of the school, refused to accept made by the Students' Union.
| A．either | B．neither | C．any | D．none |
Mary is short__________ her brother is very tall.
| A．still | B．nor | C．while | D．when |
There was less food for birds and also for the Prairie dog, an______holes in the ground.
| A．livs | B．is living | C．living | D．lived |
--Do you mind if I smoke here?
--____________.
A. Sure. Go ahead B. No. Go ahead C. Yes. Please