In order to keep the balance of ecosystem, every possible means _______to deal with the problems of the over-exploiting of natural resources.
A．has tried B．has been tried C．have taken D．have been taken
We all thought that Betty could have run _______ if she had worn the sports-shoes that day.
A．even faster B．more slower C．much quickly D．still fastest
In that traffic accident last night the man who hit five people in a row had drunk so much that he could no longer_______ between fantasy and reality.
A．distinguish B．disguise C．disturb D．disgust
Mr. Andrew taught his students how to develop the basic skills in the physics class, ______ everything through jokes and experiments.
A．to explain B．explained C．explaining D．explains
Mr. Bryan is a/an _______ secretary in our office, for he is able to do tasks successfully, without wasting time or energy.
A．effective B．efficient C．flexible D．sufficient
There was enough evidence to prove that the explosion in Robinson’s house _______ the leak of natural gas.
A．resulted in B．resulted from C．led to D．contributed to
