【问】 If you____the bus，we____their concert in the theatre now.
 A. miss... are enjoying____B. didn’t miss... are enjoying
 C. had not missed... would be enjoying D. had not missed... were enjoying
 关于虚拟条件句，据我所知，在时态上有下列四种表达方法：
 A. If there were no air，there would be no life on the earth.(与现在事实相反)
 如果没有空气，地球上就不会有生命。
 B. If I had married her，I would have been unhappy.(与过去事实相反)要是那时我跟她结了婚的话，那我是很不幸的。
 C. If the string should break，the ball would fly away from your hand. (预料与将来的事
 实相反)
 如果绳子万一断了，球就会脱离你的手飞走。
 D. If it rained tomorrow，we’d stay at home. (LEG)(预料与将来的事实相反)
 要是明天下雨的话，我们就待在家里。
 我觉得上面的试题不符合这四种情况的任何一种，这是怎么回事呢?
 【答】 世界上的事物或事件是复杂的，而事物或事件之间的关系更是复杂的。你所提到的虚拟条件句中的时态配合情况是最基本的。有时候，条件从句与主句所表示的时间是不一致的。举例来说，有人要你用英语表达这样一个意思：
 要是那时我跟她结了婚的话，那我现在会很不幸的。
 你将怎么办呢?你上面提到的那四种时态配合都无法表达这种时间关系。在这种情况下，只能借助于英语动词时态的调整。注意：汉语是通过词汇手段来表达这种关系的，而英语是通过语法手段——动词的时态来表达这种关系的。下面是一些常见的错综时间的表达方法：
 A.从句表示与过去的事实相反，主句表示与现在正在发生的情况相反
 1. If you had not missed the bus，we would be enjoying their concert now. (上道试题的正确答案)
 要不是你误了公共汽车的话，那我们现在正在听他们的音乐会呢。
 2. If I hadn’t sent some money to my friend last month he would be having a terrible time.
 要是上个月我没有给我的朋友寄去一些钱的话，那他目前就非常困难了。
 3. If the weather had been more favorable，the crops would be growing still better.
 如果以前的天气好一些，那么现在的庄稼长得就会更好一些。
 4. If it hadn’t been for the doctor’s care，I should not be speaking to you now.(Doyle)
 要不是有了医生的照料，我现在就不能和你讲话了。
 5. If Maxim had been there I should not be lying as I was now. (Du Maurier)
 如果那时马克西姆在那儿的话，我就不会象现在这样躺着了。
 B.从句表示与过去的事实相反，主句表示与现在的事实相反：
 1. If I had learned French I would be albe to interpret for our French friends.要是我以前学过法语的话，那我现在就能给我们的法国朋友当翻译了。
 2. If you had followed the doctor's advice，you would be quite well.
 如果当时你听了大夫的劝告，你现在就会完全康复了。
 3. If I had had your advantages，I'd be better now. (LEG)
 要是那时我有你的有利条件，我现在就会好得多了。
 4. Sue would be alive today if the doctor had come sooner last night. (IME)
 如果昨天晚上医生早点儿来的话，休今天还会活着。
 5. If you'd listened to me，you wouldn't be in such trouble now. (LDCE)要是你听了我的话，你现在就不会有这样的麻烦了。
 C.从句表示与过去正在发生的情况相反，主句表示与现在正在进行的情况相反：
 If we hadn't been working hard in the past few years，things wouldn't be going so smooth-ly.
 要是过去几年我们没有作艰苦努力，那么现在一切都不会进行得这样顺利。
 D.从句表示与过去的事实相反，主句表示将来不可能实现的事件：
 If I had earned some money last summer，I would go on a vacation next month.如果我去年夏天挣了点钱的话，我下个月就会去渡假了。
 E.从句表示将来实现可能性较小的条件或者说不大确定的条件，从句用should+动词原形，主句用祈使句或一般将来时。这种结构常常用来表示礼貌的请求或建议：
 1. If he should call，tell him I'll ring back.(LEG)
 要是他来电话，告诉他我将给他回电话。
 2. If I should see him，I'll ask him to ring you.(LEG)
 要是我看到他，我将请他给你回电话。
 请做下面的英语试题
 1. television had been invented a years ago. nations be significantly
 more homegeneous than now? (TOEFL， 88.10)
 2. If he had taken my advice，he________ a scientist now.
 A. will be B. is C. would be D. would have been
 3. If Tom started this morning，he____everything ready last night.
 A. would get B. would have got
 C. will have got D.got
 4. If the United States had built more homes for poor people in 1955，the housing prob-lems now in some parts of this country________ so serious.
 A. wouldn't be B. will not have been
 C. wouldn't have been D. would have not been