—Why does the lake smell terrible?
—Because large quantities of water .
A. have polluted B. have been polluted
C. is being polluted D. has been polluted
—Hi, Tom, why are you looking so tired?
—I'm tried. Because I ______ the living room all day.
A. painted B. have been painting
C. have painted D. had painted
__________ is troubling me is __________ I don’t understand __________ he said.
A. What; that; what B. It; that; what
C. That; that; what D. what; that; which
______________________, I would have given you his address.
A. If you asked me
B. You had asked me
C. Should you have asked me
D. Had you asked me
As a teacher, he knows exactly how to his ideas to the students.
A. consult B. display
C. convey D. comfort
________ you can finish the task on time, it doesn't matter how you do it.
A．So long as B．As soon as
C．As well as D．So far as
