“條件”表達法是中學(xué)英語中相當重要的語言現(xiàn)象，也是高考測試的重點和難點，為使同學(xué)們更好的復(fù)習(xí)和運用，減少失誤，現(xiàn)就其相關(guān)知識與考點作如下歸納分析：
條件即一個動作或一種情況發(fā)生存在的前提，有真實條件和非真實之分。簡述如下：
一 從句
常用來引導(dǎo)條件從句的連詞有：if，unless，even if ，in case ，as long as，so long as，so far as ，
On condition that，
1 考查in case 引導(dǎo)條件句的用法
[NMET2000] I don’t think I’ll need any money but I ‘ll bring some_____.
A at last B in case C once again D in time
【解析】本題考查in case 引導(dǎo)條件句的用法,答案為: B ..in case引導(dǎo)條件句,其意為“假使；以防（萬一）”。其位置較為靈活，可置于句首或句尾 。其時態(tài)常用一般現(xiàn)在時表示將來，但也可用“should﹢動詞原形”。
例如：Be quiet in case you should wake the baby
【測試演練】（2000春季京皖卷）(答案: C)
John may phone tonight。I don’t want to go out____he phones.
A as long as B in order that C in case D so that
2考查if 引導(dǎo)條件句的用法
[NMET2000] The WTO can’t live up to its name____ it does not include a country that is home to one fifth of mankind
A as long as B while C if D even though
【解析】本題考查If 引導(dǎo)條件句的用法,答案為: C. 在if 引導(dǎo)的條件句中,應(yīng)注意 時態(tài)的對應(yīng)性,一般來說,if引導(dǎo)的條件句常用一般現(xiàn)在時或現(xiàn)在完成時表示將來而主句常用一般將來時,祈使句或情態(tài)動詞的一般式.
【測試演練】(MET1992) (A)
If city noises ___ from increasing, people ____ shouted to be heard even at the dinner table
20 years from now .
A are not kept ;will have to B are not kept ; have to
C do not keep ;will have to D do not keep; have to
3 考查unless 引導(dǎo)條件句的用法
[NMET1992] You will be late ___you leave immediately.
A unless B until C if D or
【解析】答案：A 。unless 引導(dǎo)的從句，意義為“除非，如果不”相當于“if….not”
4考查if 引導(dǎo)省略條件句的用法
[上海高考卷1998] If ____the same attention again, he is sure to get well
A giving B give C given D being given
【解析】答案：C .在條件狀語從句中,如果從句的主語與主句的主語一致,且從句中有系動詞be,可以將從句主語及be 省去,構(gòu)成省略.
5考查if省略的條件句的用法
[上海高考卷1994] it rain tomorrow ,we would have to put off the visit to the Yangpu Bridge
A Were B Should C Would D Will
【解析】答案：B .本題屬于虛擬語氣倒裝形式.若省略if可將were,( had ,should )提到句首
變?yōu)榈寡b形式。
If I were at school again，I would study harder
→Were I at school again，I would study harder
If you had come earlier，you would catch the bus。
→Had you come earlier，you would catch the bus。
【易錯點解析】若省略的條件句中的謂語動詞是否定形式時，不能用動詞縮寫形式。
誤：Weren’t it for the expense ,I would go abroad now
正;Were it not for the expense ,I would go abroad now
條件即一個動作或一種情況發(fā)生存在的前提，有真實條件和非真實之分。簡述如下：
一 從句
常用來引導(dǎo)條件從句的連詞有：if，unless，even if ，in case ，as long as，so long as，so far as ，
On condition that，
1 考查in case 引導(dǎo)條件句的用法
[NMET2000] I don’t think I’ll need any money but I ‘ll bring some_____.
A at last B in case C once again D in time
【解析】本題考查in case 引導(dǎo)條件句的用法,答案為: B ..in case引導(dǎo)條件句,其意為“假使；以防（萬一）”。其位置較為靈活，可置于句首或句尾 。其時態(tài)常用一般現(xiàn)在時表示將來，但也可用“should﹢動詞原形”。
例如：Be quiet in case you should wake the baby
【測試演練】（2000春季京皖卷）(答案: C)
John may phone tonight。I don’t want to go out____he phones.
A as long as B in order that C in case D so that
2考查if 引導(dǎo)條件句的用法
[NMET2000] The WTO can’t live up to its name____ it does not include a country that is home to one fifth of mankind
A as long as B while C if D even though
【解析】本題考查If 引導(dǎo)條件句的用法,答案為: C. 在if 引導(dǎo)的條件句中,應(yīng)注意 時態(tài)的對應(yīng)性,一般來說,if引導(dǎo)的條件句常用一般現(xiàn)在時或現(xiàn)在完成時表示將來而主句常用一般將來時,祈使句或情態(tài)動詞的一般式.
【測試演練】(MET1992) (A)
If city noises ___ from increasing, people ____ shouted to be heard even at the dinner table
20 years from now .
A are not kept ;will have to B are not kept ; have to
C do not keep ;will have to D do not keep; have to
3 考查unless 引導(dǎo)條件句的用法
[NMET1992] You will be late ___you leave immediately.
A unless B until C if D or
【解析】答案：A 。unless 引導(dǎo)的從句，意義為“除非，如果不”相當于“if….not”
4考查if 引導(dǎo)省略條件句的用法
[上海高考卷1998] If ____the same attention again, he is sure to get well
A giving B give C given D being given
【解析】答案：C .在條件狀語從句中,如果從句的主語與主句的主語一致,且從句中有系動詞be,可以將從句主語及be 省去,構(gòu)成省略.
5考查if省略的條件句的用法
[上海高考卷1994] it rain tomorrow ,we would have to put off the visit to the Yangpu Bridge
A Were B Should C Would D Will
【解析】答案：B .本題屬于虛擬語氣倒裝形式.若省略if可將were,( had ,should )提到句首
變?yōu)榈寡b形式。
If I were at school again，I would study harder
→Were I at school again，I would study harder
If you had come earlier，you would catch the bus。
→Had you come earlier，you would catch the bus。
【易錯點解析】若省略的條件句中的謂語動詞是否定形式時，不能用動詞縮寫形式。
誤：Weren’t it for the expense ,I would go abroad now
正;Were it not for the expense ,I would go abroad now