Among the crises that face humans ________ the lack of natural resources.
A.is B.are C.is there D.are there
He asked them to come to his office one ________.
A.at no time B.at one time C.at a time D.in no time
In the global economy, a new drug for cancer, ________ it is discovered, will create many economic possibilities around the world.
A.whatever B.whoever
C.wherever D.whichever
________our manager objects to Tom's joining the club，we shall accept him as a member.
A.Until B.Unless C.If D.After
My brother will have to take care of you. I'll call him today and he ______ you.
A.has expected B.will have expected
C.expects D.will be expecting
_______ an important decision more on emotion than on reason, you will regret it sooner or later.
A.Based B.Basing C.To base D.Having based
