—___________is the World Cup held?
—Every 4 years.
| A．How soon | B．When |
| C．How often | D．How long |
______ trees are cut down in the forests every year.
| A．Thousand | B．Thousands |
| C．Thousands of | D．Thousand of |
The population of the world in 20 century became very much _____than that in 19 century.
| A．bigger | B．lager |
| C．greater | D．more |
If I’m free,I’d like to spend ______holiday in Dunhuang.
| A．three days | B．a three-day | C．three-day | D．three day |
----_______ do you have out with your friends?
----Once a week.
| A．How long | B．How often | C．How many | D．How soon |
The accident took place ______ a cold February evening.
| A．on | B．in | C．At | D．for |