It is reported that 40 percent of the land in Brazil________covered with trees.
| A．is | B．was | C．are | D．were |
In order to do something meaningful, it’s necessary that you _______ determine what is really important.
| A．must | B．will |
| C．need | D．should |
It is strange that such a thing ______ in your school．
| A．will happen | B．happens |
| C．should happen | D．happened |
—What a pity! Their experiment is a failure.
—They ________ better under more favorable conditions.
| A．should have done | B．could have done |
| C．must have done | D．may have done |
more energy to my study instead of being crazy about Internet games, I would be sitting in a comfortable office now．
| A．If I devoted | B．Had I devoted |
| C．Would I be devoted | D．Should I be devoted |
Jack is a great talker. It's high time that he ________ something instead of just talking.
| A．will do | B．has done |
| C．do | D．did |