(一) 与现在的事实相反
What type of automobile would you buy _____ ？
［A］ if you have free choice to choose the cars available today
［B］ if you are free to choose among all the cars available today
［C］ if all cars available were free to be chosen by you
［D］ if you were free to choose among all the cars available today
(二)与过去的事实相反(有时主句中的should have done表示责备或后悔)
_____ ，he would have come to class.
［A］ If Mike is able to finish his homework
［B］ Would Mike be able to finish his homework
［C］ If Mike could finish his homework
［D］ If Mike had been able to finish his homework
If the United States had not entered the Second World War，probably the 1940 unemployment rate of 14％ _____ still further.
［A］ would rise
［B］ would risen
［C］ would have risen
［D］ had risen
Topgrade ［A］ diamonds had not ［B］ increased so sharply ［C］ in value in the late seventies ［D］ if one company had not controlled almost all of the world’s supply.
(三)与将来的事实相反
The report would be ［A］ released last January if new developments had not ［B］ made it necessary to revise all conclusions drawn from ［C］ the first series of ［D］ experiments.
It is said Tom will go to an appointment tommorrow. If he were to come tomorrow, I _____ ask him to go to your place.
［A］ will
［B］ would
［C］ shall
［D］ might
If you _____ to see Mary，what would you tell her?
［A］ are
［B］ will be going
［C］ must
［D］ were
(四)与将来的事实可能相反
(1) If it should rain tomorrow, I would stay at home. 要是万一 明天下雨，我就呆在家里不出去。 事实上 现在天气很好，明天下雨的可能性应该不大，不过也说不准。
(2) If I should see her next Monday, I would tell her about it. 如果下周一我能见到她的话我就把这件事告诉她。
三、例题解析
D为正确答案。
D为正确答案。
C为正确答案。
B错。改为would have not。
A错。改为would have been。
B为正确答案。
D为正确答案。
