About _______ of the surface of the earth _______ covered with water.
| A．three quarter, is | B．three quarters, has | C．three quarters, is | D．three quarter, are |
There are many kinds of birds in Australia,and over 140 species of snakes,many of
____are extremely dangerous.
| A．them | B．which |
| C．what | D．those |
Private cars are required to take turns off roads one out of five weekdays ____the
traffic pressure.
| A．to reduce | B．reducing |
| C．reduce | D．reduced |
There is a saying ____swimming is a good
way to keep fit.
| A．which | B．what | C．that | D．where |
This is a city which lives for today while ____ by its past.
| A．surround | B．surrounding |
| C．surrounded | D．to surround |
In September 2008,China’s key milestone in space travel _____when Zhai Zhigang
conducted the first space walk.
| A．reached | B．was reached |
| C．has reached | D．had been reached |