Collecting stamps as a hobby___________ increasingly popular during the past fifty years.
| A．becomes | B．became | C．has become | D．had become |
Was it not until you began to work ____ how much time you had wasted?
| A．did you realize | B．that you realized |
| C．did you not realize | D．that you didn’t realize |
_____ some teenagers don’t realize is ____ difficult life can be after they get addicted to drugs.
| A．What; how | B．That; how | C．That; what | D．What ; what a |
When I got off the crowded bus, I found my pocket _____ and the disk in it with the important documents gone.
| A．picked | B．stolen | C．missing | D．lost |
The newly discovered star was named _____ a Chinese astronomer ____ honor of his contributions to astronomy.
| A．for; in | B．after; for | C．as; in | D．after; in |
Hundreds of people gave their lives in _____ of freedom.
| A．protection | B．guard | C．defense | D．favor |