-Why does the lake smell terrible?
-Because large quantities of water .
| A．is being polluted | B．have been polluted |
| C．is polluted | D．has been polluted |
—Do you think George has passed the driving test?
—No. If so, he ________ his car to our college yesterday.
| A．would drive | B．drove |
| C．would have driven | D．had driven |
(2013·全国Ⅱ，6)Since nobody gave him any help, he ________ have done the research on his own.
| A．can | B．must |
| C．would | D．need |
—You needn't take an umbrella.It isn't going to rain.
—Well, I don't know.It ________ do.
| A．might | B．need |
| C．would | D．should |
When I was a child, I ________ watch TV whenever I wanted to.
| A．should | B．could |
| C．must | D．need |
I should not have laughed if I ________ you were serious.
| A．thought | B．would think |
| C．had thought | D．have thought |