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 |
Eating too much fat can ________ heart disease and cause high blood pressure.
| A．result from | B．contribute to | C．attend to | D．devote to |
Reducing the gap between the rich and the poor is one of the main ___________meeting the government.
| A．alarms | B．stresses | C． pressures | D．challenges |
How I wish we studied ________there are fewer exams .
| A．which | B．that | C．where | D．when |
On July 20, 1969, Neil Armstrong become the first man _________foot on the moon .
| A．setting | B．set | C．to setting | D．to set |
The timetable says the school bus _________ here for the first trip at 6:30 am.
| A．will leave | B．left | C．is leaving | D．leaves |