??"在……條件下發(fā)生了或?qū)l(fā)生……事"，這是人們?cè)谡Z(yǔ)言交流過(guò)程中常見(jiàn)的句式。英語(yǔ)中通常用if引導(dǎo)的從句表達(dá)這一概念，但決不限于if條件句。英語(yǔ)中的條件狀語(yǔ)有多種表現(xiàn)形式，體現(xiàn)了英語(yǔ)語(yǔ)言的豐富多彩。
??1?用介詞短語(yǔ)表達(dá)
??能用來(lái)表示條件的介詞主要有with，without，but for等。注意：如果with， without短語(yǔ)所陳述的情況完全有可能成為事實(shí)，動(dòng)詞用陳述語(yǔ)氣；如果所陳述的情況與事實(shí)相反，則用虛擬語(yǔ)氣。含but for的句子一般用虛擬語(yǔ)氣。但介詞短語(yǔ)本身常常并不表示條件，而是隱含了條件。例如：
??Without revolutionary theory there can be no revolutionary movement．沒(méi)有革命理論，就不可能有革命運(yùn)動(dòng)。（陳述語(yǔ)氣）
??Without air，the earth would undergo extreme changes in temperature．沒(méi)有空氣，地球就會(huì)出現(xiàn)極冷極熱的變化。（虛擬語(yǔ)氣）
??With a little care you could have avoided this accident．如果小心一點(diǎn)，你本可以避免這次事故。
??But for my brother's help，I would not have finished the work．如果不是我兄弟幫忙，我就不會(huì)完成這項(xiàng)工作。
??Such floods would have caused thousands of deaths in the past．（in the past隱含了if thefloods had occurred in the past）這樣的洪水在過(guò)去會(huì)造成數(shù)千人的死亡。
??2?用短語(yǔ)連接詞引出
??能引起條件句的短語(yǔ)有：on condition that（條件是），as long as（只要），in case（假使），but that（要不是）等。其中含but that從句的主句謂語(yǔ)動(dòng)詞須用虛擬語(yǔ)氣。例如：
??I will lend you this book on condition that you return it to me before Friday．如果你能在周五以前還給我，我就借你這本書(shū)。
??He would have said no but that he was afraid．要不是害怕，他就會(huì)說(shuō)"不"了。
??This project can go on as long as it is not raining．只要不下雨，工程就可以繼續(xù)進(jìn)行。
??3?用分詞引出
??英語(yǔ)中，被用來(lái)表示條件的詞還有providing（that）（假如），provided（that）（假如）， supposing（that）（假定），given（假如）。這組詞都是由動(dòng)詞演變而來(lái)，除given外，都已被認(rèn)定為連詞。例如：Supposing it rains，what shall we do？如果下起雨來(lái)，我們?cè)趺崔k？
??Provided ／Providing（that）there is no op- position，we shall hold the meeting here．如果沒(méi)有不同意見(jiàn)，我們將在這里舉行會(huì)議。
??Given good health，I hope to finish the
work this year．假若健康狀況良好，我希望今年完成這項(xiàng)工作。
??4?隱含在上下文中
??有些假設(shè)條件沒(méi)有明示，需根據(jù)上下文加以判斷。例如：
??He can't be ill or he wouldn't have come．他不可能生病了，否則他不會(huì)來(lái)的。（隱含了．．．if he were ill，．．．）
??She had intellect，otherwise I should have scorned her．她聰明，否則我就會(huì)看不起她。（隱含了．．．if she had not had intellect，．．．）
??He would have given you more help，but he was very busy．他本來(lái)要給你更多的幫助，只是他太忙了。（隱含了．．．if he had not been busy，．．．）
??注意：含有or，otherwise的句子，謂語(yǔ)動(dòng)詞并不都是虛擬語(yǔ)氣，要根據(jù)所表達(dá)情況的真實(shí)與否而定。如下面的句子就不必用虛擬語(yǔ)氣。
??Wear your coat or you'll be cold．穿上外套，要不然你會(huì)冷的。
??
??Hand in your application now，otherwise you will miss the opportunity．現(xiàn)在就把申請(qǐng)交上來(lái)，否則的話你就會(huì)失去機(jī)會(huì)的。
??Exercise：Fill in the blanks with the proper words．
??1． ____ he saw it，he would not have believed it．（But for ／But that ／Suppose）
??2．Motors will run well ____ they aremaintained regularly．（unless ／otherwise ／provided）
??3．But for your help，I ____?．（had failed ／should have failed）
??4．I am getting old-otherwise I____ her．（will keep ／would keep ／have kept）
??5．He will do the work ____?you pay him．（providing ／unless）
??6．The old woman would have been drowned but that a passer-by ____?her out of the water．（had dragged ／would drag ／ dragged）
??7．We ____?better under more favorable conditions．（could have done ／had done ／ did）
??8． ____ he arrives before I get back， please ask him to wait．（In case ／Given）
??9．He would have come to see you，but he____ very busy at the time．（were ／was ／ is）
??10．A less brave man ____ to work in the enemy headquarters．（did not dare ／wouldn't have dared ／dared not）
Key：1．But that 2．provided 3．should have failed 4．would keep
??5．providing 6．dragged 7．could have done 8．In case 9．was ??10．wouldn't have dared
??1?用介詞短語(yǔ)表達(dá)
??能用來(lái)表示條件的介詞主要有with，without，but for等。注意：如果with， without短語(yǔ)所陳述的情況完全有可能成為事實(shí)，動(dòng)詞用陳述語(yǔ)氣；如果所陳述的情況與事實(shí)相反，則用虛擬語(yǔ)氣。含but for的句子一般用虛擬語(yǔ)氣。但介詞短語(yǔ)本身常常并不表示條件，而是隱含了條件。例如：
??Without revolutionary theory there can be no revolutionary movement．沒(méi)有革命理論，就不可能有革命運(yùn)動(dòng)。（陳述語(yǔ)氣）
??Without air，the earth would undergo extreme changes in temperature．沒(méi)有空氣，地球就會(huì)出現(xiàn)極冷極熱的變化。（虛擬語(yǔ)氣）
??With a little care you could have avoided this accident．如果小心一點(diǎn)，你本可以避免這次事故。
??But for my brother's help，I would not have finished the work．如果不是我兄弟幫忙，我就不會(huì)完成這項(xiàng)工作。
??Such floods would have caused thousands of deaths in the past．（in the past隱含了if thefloods had occurred in the past）這樣的洪水在過(guò)去會(huì)造成數(shù)千人的死亡。
??2?用短語(yǔ)連接詞引出
??能引起條件句的短語(yǔ)有：on condition that（條件是），as long as（只要），in case（假使），but that（要不是）等。其中含but that從句的主句謂語(yǔ)動(dòng)詞須用虛擬語(yǔ)氣。例如：
??I will lend you this book on condition that you return it to me before Friday．如果你能在周五以前還給我，我就借你這本書(shū)。
??He would have said no but that he was afraid．要不是害怕，他就會(huì)說(shuō)"不"了。
??This project can go on as long as it is not raining．只要不下雨，工程就可以繼續(xù)進(jìn)行。
??3?用分詞引出
??英語(yǔ)中，被用來(lái)表示條件的詞還有providing（that）（假如），provided（that）（假如）， supposing（that）（假定），given（假如）。這組詞都是由動(dòng)詞演變而來(lái)，除given外，都已被認(rèn)定為連詞。例如：Supposing it rains，what shall we do？如果下起雨來(lái)，我們?cè)趺崔k？
??Provided ／Providing（that）there is no op- position，we shall hold the meeting here．如果沒(méi)有不同意見(jiàn)，我們將在這里舉行會(huì)議。
??Given good health，I hope to finish the
work this year．假若健康狀況良好，我希望今年完成這項(xiàng)工作。
??4?隱含在上下文中
??有些假設(shè)條件沒(méi)有明示，需根據(jù)上下文加以判斷。例如：
??He can't be ill or he wouldn't have come．他不可能生病了，否則他不會(huì)來(lái)的。（隱含了．．．if he were ill，．．．）
??She had intellect，otherwise I should have scorned her．她聰明，否則我就會(huì)看不起她。（隱含了．．．if she had not had intellect，．．．）
??He would have given you more help，but he was very busy．他本來(lái)要給你更多的幫助，只是他太忙了。（隱含了．．．if he had not been busy，．．．）
??注意：含有or，otherwise的句子，謂語(yǔ)動(dòng)詞并不都是虛擬語(yǔ)氣，要根據(jù)所表達(dá)情況的真實(shí)與否而定。如下面的句子就不必用虛擬語(yǔ)氣。
??Wear your coat or you'll be cold．穿上外套，要不然你會(huì)冷的。
??
??Hand in your application now，otherwise you will miss the opportunity．現(xiàn)在就把申請(qǐng)交上來(lái)，否則的話你就會(huì)失去機(jī)會(huì)的。
??Exercise：Fill in the blanks with the proper words．
??1． ____ he saw it，he would not have believed it．（But for ／But that ／Suppose）
??2．Motors will run well ____ they aremaintained regularly．（unless ／otherwise ／provided）
??3．But for your help，I ____?．（had failed ／should have failed）
??4．I am getting old-otherwise I____ her．（will keep ／would keep ／have kept）
??5．He will do the work ____?you pay him．（providing ／unless）
??6．The old woman would have been drowned but that a passer-by ____?her out of the water．（had dragged ／would drag ／ dragged）
??7．We ____?better under more favorable conditions．（could have done ／had done ／ did）
??8． ____ he arrives before I get back， please ask him to wait．（In case ／Given）
??9．He would have come to see you，but he____ very busy at the time．（were ／was ／ is）
??10．A less brave man ____ to work in the enemy headquarters．（did not dare ／wouldn't have dared ／dared not）
Key：1．But that 2．provided 3．should have failed 4．would keep
??5．providing 6．dragged 7．could have done 8．In case 9．was ??10．wouldn't have dared