My father and my mother have been married for 30 years, and never once ______ with each other.
| A．they have quarrelled | B．did they quarrel |
| C．had they quarrelled | D．have they quarrelled |
She was so _____ in her job that she didn’t hear anybody knocking at the door.
| A．devoted | B．attracted | C．drawn | D．absorbed |
Our professor told us that salt water _____ at a lower temperature than fresh water.
| A．is freezing | B．was frozen | C．freezes | D．froze |
Nowhere else in the world _____ more friendly people than in China.
| A．you will find | B．you can find |
| C．can you find | D．you may have found |
—Brad was Jane’s brother!
—_____ he reminded me so much of Jane!
| A．No wonder | B．Above all | C．No doubt | D．Of course |
Many people claim that they have seen UFO with their own eyes, _____ I personally doubt.
| A．when | B．where | C．that | D．which |