Our country should set up more national parks animals can live freely.
| A．when | B．which | C．where | D．whose |
______ with the size of the whole earth, the highest mountain does not seem high at all.
| A．When compared | B．While comparing |
| C．Compare | D．Comparing |
-- How long do you think it will be ______ the bus arrives here?
-- No more than five minutes.
| A．when | B．before | C．since | D．after |
Making a proper choice ______ the future will probably make much difference in our life.
| A．concerning | B．to concern | C．concerned | D．having concerned |
In Canada, cross country skiing is a popular sport among people ______ they can enjoy excitement and adventure.
| A．that | B．where | C．whom | D．which |
According to what he complained about, something must have gone wrong with the computer, ______?
| A．mustn’t it | B．didn’t he | C．hasn’t he | D．didn’t it |