While every possible means __________ to prevent the river pollution, the river in my hometown has still not been restored to its past beauty.
| A．is tried | B．are tried |
| C．has been tried | D．have been tried |
-If you have time tonight，I’d like to invite you to a ball.
-That’s very nice of you，but are you ____?
| A．free | B．careful | C．serious | D．true |
How pleased the detective was _____ what his customer told him
| A．hearing | B．heard | C．to hearing | D．to hear |
-What did you think of ______ president?-I didn’t care for him at first，but after ____ time I get to like him.
| A．the； a | B．/； the | C．the； the | D．/； a |
How pleasant the picture is to _______！
| A．be looked | B．for looking at | C．looking at | D．look at |
In the 16-19 age group，32 of women smoke ______ 28 of men.
| A．comparing to | B．comparing with |
| C．compared to | D．compare with |