虚拟语气在if条件从句中的用法在if 引导的虚拟条件句中，若表示与现在事实相反，从句谓语用“动词过去式（be 的过去式用were ）,主句谓语用“would(should, could, might)+have+过去分词”；若表示与将来事实相反，从句谓语用“动词过去式（were to +动词原形，should+动词原形）”，主句谓语用“would(should, could, might)+动词原形”。
若把从句中were, should 或had移到句首，可省略从句的连词 if 并使用倒装语序.① If my lawyer ___here last Saturday ,he ____me from going.(NMET’89)A. had been ;would have preventedB. had been ; would preventC. were ;would preventD. were;would have prevented②---If he ____,he ____that food.--Luckily he was sent to the hospital imme diately.(MET’93)A. was warned ;would not takeB. had been warned ;would not have takenC. would be warned; had not takenD. would have been warned; had not taken③I didn’t see your sister at the meeting .If she ___,she would have met my brother.(NMET’94)A. has comeB. did comeC. cameD. had come④____it rain tomorrow, we would have to put off the visit to the Yangpu Bridge.(1994,上海)A. WereB. shouldC. WouldD. Will2．考查通过上下文或介词短语表示虚拟条件的虚拟语气的用法在英语中，有时假设的条件不是通过if 条件句表达出来，而是通过上下文或without, but for 等介词构成的短语表达，其谓形式要根据所假设的时间，与if 从句所表达的时间对应，确定主句谓语形式。
[考例]⑤Without electricity human life ____quite differenttoday.(NMET’91)A. isB. will beC. would have beenD. would be⑥I told Sally how to get here ,but perhaps I ____for her .(NMET’94)A. had to write outB. must have written it outC. should have written it outD. ought to write it out⑦without the air to hold some of the sun’s heat, the earth at night___, too cold for us to live.(1997,上海)A. would be freezing coldB. will be freezing coldlyC. would be frozen coldD. can freeze coldly3.考查虚拟语气在as if 引导的方式状语或表语从句中的用法As if 引导的方式状语或表语从句，谓语动词用“一般过去式”表示与现在事实相反；用“would(might, could)+动词原形”表示与将来事实相反。
]⑧The two strangers talked as if they ____friends for years.(1993,上海)A.should beB.would beC.have beenD.had been⑨When a pencil is partly in a glass of water, it looks as if it_____.(NMET’95)A.breaksB.has brokenC.were brokenD.had been broken4.考查虚拟语气在wish 后面宾语从句的用法Wish 后面的从句，谓语用“过去式”表示现在不能实现的愿望；用“had+过去分词”表示过去没有实现的愿望；用“would(should,could) +动词原形”表示将来不能实现的愿望。
[考例]⑩ I wish I_______you yesterday.(Met”88)A. seenB.did seeC.had seenD.were to see5．考查虚拟语气用于宾语从句的用法。
在及物动词insist ,order ,require ,demand, command等后面，宾语从句所说的是尚未发生的事，所以谓语要用与将来事实相反的虚拟语气，即“should+动词原形”表达。
其中should 可以省略。
考例（11）The guard at the gate insisted that every body _______therules.(MET’85)A. obeysB. obeyC. will obeyD. would obey(12) The officer ordered that everybody ____part in the campaign. (1986.上海)A. takeB. taken c. took D. will take答案:1-5 ABDBD 6-10 CADCC 11-12 BA1． Elize remembers everything exactly as if it _______yesterday.(2006全国卷一)A. was happening B .happens C. has happened D. happened解析:D. 考察虚拟语气.as if 引导的从句通常用虚拟语气.又因 remember知与现在事实相反,因此用一般过去时.2. _____fired, your health care and other benefits will not be immediately cut off. (2006湖北)A. would you beB. should you beC. could you beD. might you be解析:B考察虚拟语气的倒装.if 引导的条件状语从句,如果用虚拟语气,可以把if 省略,将助动词were, had 或should 提前,构成倒装.3. I was on the highway when this car went past followed by a police car. They ____at least 150 kilometers an hour.(2005 重庆)A. should have been doingB. must have been doingC. could have doneD. would have done解析:B 考察虚拟语气.表推测4. He paid for a seat, when he ____have entered free.(2005 山东)A. couldB. wouldC. mustD. need解析: A. 考察虚拟语气情态动词的用法5. Mr.White ______at 8:10 for the meeting, but he didn’t show up.(2004全国卷三)A. should have arrivedB. should arriveC. should have had arrivedD. should be arriving解析: A 本题考察虚拟语气及责备的用法. Should have done 结构,表过去原本该做而没做的事.高考预测：1. What would have happened if you____her child ?A.hadn’t helpedB. couldn’t helpC. wouldn’t helpD. didn’t help解析：A表示过去时间的虚拟是条件从句，用过去完成时，主句用would (should)+have + 动词原形。
2. If I ___with her last summer, I ___with her now .A. worked ---am getting on very wellB. had worked ---will get on very wellC. had worked ---would have got on very wellD. have worked ---will get on very well.解析：B。
本题是混合式虚拟语气。
主句是对现在时间的虚拟。
3. The boss ordered that he ___the work at onceA. startsB. will startC. would startD. start解析：D order, suggest 等词后的宾语从句，要用虚拟语气，构成为should +v, should可以省略。
4. The little hero’s pale face suggested he ________dead.A. isB. wasC. should beD. be解析；B 不作建议讲时，宾语从句谓语不用虚拟语气。
5._________I known it, I should have told him .A. haveB. hadC. havingD. If解析：B 这是一个与过去事实相反的虚拟语气，如非真实性条件句谓语含had ,should ，were 时，可将这些词提到句首，省去if.6.If you had gone to a doctor, you ________all right now.A. would not comeB. might not comeC. should not comeD. could not come解析：C 表示与将来事实相反的虚拟语气句。