_____ he thought he was helping us with the work, he was actually in the way．
| A．Since | B．When | C．Because | D．If |
Don’t you think that______________ is no use promising without doing?
| A．this | B．that | C．it | D．what |
The children were warned of not being too _______ about things you are not supposed to know.
| A．strange | B．amusing | C．curious | D．satisfied |
Americans eat____ vegetables per person today as they did in 1990.
| A．more than twice | B．as twice as many |
| C．twice as many as | D．more than twice as many |
Students ______ remain in their seats until all the exam papers have been collected.
| A．must | B．shall | C．may | D．can |
The atmosphere of the earth ______ us from the strong sun light.
| A．prevents | B．keeps | C．stops | D．protects |