Since the new speed limits ______，the number of accidents in the area has fallen strikingly．
| A．were introduced |
| B．introduced |
| C．have been introduced |
| D．have introduced |
—I'm sorry, but I didn't mean __________ out your secret.
—But you know, letting out one's secret means __________ one's feelings.
| A．to let; to hurt | B．letting; hurting |
| C．to let; hurting | D．letting; to hurt |
Remember __________ the book when you have finished it.
| A．putting back | B．having put back |
| C．to put back | D．to have put back |
—Robert is indeed a wise man.
—Oh, yes. How I regretted __________ his advice!
| A．to take | B．to have not taken |
| C．taking | D．not having taken |
Jiaxing is such a beautiful city that it is well worth __________.
| A．visit | B．visiting |
| C．visited | D．to visit |
You can't imagine the difficulty he __________ into the cold river and saving the drowning girl.
| A．had to jump | B．had jump |
| C．had jumping | D．had jumped |