I once heard him ____ that a rainbow (彩虹) was a bridge from earth to heaven.
| A．said | B．say | C．to say | D．was saying |
Many new means__________ to prevent the river ____________.
| A．have found, from polluting |
| B．have found, from being polluted |
| C．have been found, from being polluted |
| D．has been found, from being polluted |
I like _____ in the spring when the weather is warm and everything begins to grow.
| A．this | B．that | C．these | D．it |
Is it to hold the 2010 World Exhibition _______ makes Shanghai the focus of the world?
| A．when | B．that | C．which | D．what |
We can never expect________bluer sky unless we create___________less polluted world.
| A．a; a | B．a; the | C．the; a | D．the; the |
Mike ______ have known the solutions to this problem, or he would have told us.
| A．mustn’t | B．shouldn’t | C．can’t | D．needn’t |