條件句中的虛擬語氣

　　第一節：if引導的條件句中的虛擬語氣

　　虛擬語氣表示一種不能實現的假設。該語法主要用于if條件狀語從句。

　　一、if引導的條件狀語從句的分類及虛擬條件句的判斷

　　1、可以把條件句分為兩類：

　　1).真實條件句(Sentences of Real Condition)：凡是假設的情況發生性可能很大，就是真實條件句。例如：

　　⑴、If I have time , I will help you with this work.如果我有時間會幫助你做此工作的。

　　⑵、As long as I say anything wrong, you must point it out.只要我說了什么錯話，你一定要指出來。

　　⑶、If time permits, we'll go fishing together.(如果有時間的話，我們就一起去釣魚。)

　　2).虛擬條件句(Sentences of Unreal Condition)：當假設是不大可能實現時，就是虛擬條件句。例如：

　　⑴、If I were you , I would have attended the meeting. 如果我是你的話，就去參加會議了。

　　⑵、If he had come here yesterday, he would have seen his old friend.假如他昨天來這兒的話，就會看見他的老朋友。

　　⑴、If it had rained yesterday, we would have stayed at home.(如果昨天下雨的話，我們就會留在家里。)

　　2、.if條件狀語從句中虛擬語氣的判斷

　　判斷是真實條件句還是非真實條件句。只有在非真實條件句中才使用虛擬語氣。通過句子意思，看假設的條件是否能夠實現，能夠實現是真實條件句，不能使用虛擬語氣;假設的條件不能實現則是非真實條件句，要用虛擬語氣。

　　判斷這個假設是與哪個事實相反。通常有三種情況：①與過去事實相反。②與現在事實相反。③與將來事實可能相反。

　　3、“后退一步法”

　　后退一步法是指在準確地判斷了該句與哪一事實相反后，按虛擬語氣的后退一步法處理從句謂語動詞的時態。即：在非真實條件狀語從句中，謂語動詞按正常情況“后退一步”。也就是：

　　①與過去事實相反，在從句中用過去完成時形式表示。

　　②與現在事實相反，在從句中用過去一般時形式表示。

　　③與將來事實可能相反，在從句中用過去將來時形式表示。

　　主句中則用情態動詞would, should, could 等加一個與從句一致的動詞形式。例：

　　⑴、If I had come her yesterday, I would have seen him.

　　⑵、If I were a teacher, I would be strict with my students.

　　⑶、If it should snow tomorrow, they couldn't go out.

　　4、注意事項

　　①if條件句中如有were, should, had，可以省去if，并使用倒裝語序。

　　②在現代英語中if條件狀與從句中的謂語動詞如果是be其過去形式一般用were。

二、虛擬語氣在if 引導的條件句中的用法：

　　(一)、表示與現在事實相反的情況。其句子結構為：

　　從句：if + 主語+ 動詞的過去式(be 用were) + ……

　　主句：主語+ would (should, could , might) + 動詞原形+ ……

　　例：

　　1.If I were you, I would go with him.

　　2.If the weather were fine, I would go there.

　　如果天氣好，我去那兒。(事實天氣不好)

　　3.If I were you, I would read it again.

　　如果我是你的話，我再讀一遍。(事實上我不是你)

　　4.If time permitted, I would write it again.

　　如果時間允許的話，我再寫一遍。(事實上時間不允許)

　　5.If it weren’t snowing, we wouldn’t stay in the house.

　　要是現在不下雪的話，我們就不會待在屋里。(事實上現在下雪)

　　6.What would I do if I were in your place?

　　要是我處于你地位我會怎么辦?(事實上我不在你的位置上)

　　7.If he hurried, he could catch the first bus.

　　他要是快點能夠趕上頭班公共汽車。(可是他不著急)

　　8.If it weren’t for your help, we would get into trouble.

　　如果沒有你們的幫助，我們就會陷入困境。(而事實上得到了你們的幫助)

　　9.If we had the manpower, we could open up even more land.

　　如果有人力,我們還能開更多的荒地.

　　10. If I were you, I would go with him.

　　(從句If I were you, 主句I would go with him.)

　　11. If I were you, I should buy it.

　　(從句用過去式動詞were，主句用動詞原形buy)

　　12. If I had time, I would study French.

　　(如果有時間，我會學習法文。)(從句用過去式動詞had，主句用動詞原形study)

　　13. If she knew English, she would not ask me for help.

　　(如果她懂英文，她就不必要我幫了。)(從句用過去式動詞knew, 主句用動詞原形ask)

　　注意：如果動作在進行中，主句要用："主語+ would be + 進行式動詞+ ……"

　　14. If they were here, he would be speaking to them now.

　　(從句用過去式動詞were, 主句用would be speaking)

　　(二)、表示與過去事實相反的虛擬條件句。其句子結構為：

　　從句：If + 主語+ had +過去完成式動詞+ ……

　　主句：主語+ would (should, could, might) + have +過去完成式動詞+……

例如:

　　⑴、If you had taken my advice, you would not have made such a mistake.如果你聽了我的勸告,就不會犯這樣的錯誤。(事實上你沒有聽我的勸告)

　　⑵、I shouldn’t have been able to write such good novels if I hadn’t lived among the peasants for five years.如果我不是和農民生活了五年，就不可能寫出這樣好的小說。(事實上我和農民生活了五年)

　　⑶、If you hadn’t invited me, I shouldn’t have come to the party.如果你不邀請我，我就不會來參加你的舞會。(事實上你邀請了我)

　　⑷、If it hadn’t been for your help, I shouldn’t have finished this work on time. 要是沒有你們的幫忙，我就不會按時完成了這項工作。(事實上你們幫助了我)

　　⑸、If he hadn’t broken the law, he wouldn’t have been put in prison.如果他不違法的話，就不會被打入監獄。(事實上他違法了)

　　⑹、If I hadn’t been ill yesterday, I might have come to school.昨天要是不生病，我是可能來上學的。(事實上我生病了)

　　⑺、If I had been your headmaster, I should have dismissed you from school. 我要是你們校長的話，就把你開除學籍了。(事實上我不是)

　　⑻、 If you had studied harder last term, you could have passed exam.(從句動詞用had studied, 主句動詞用have passed)如果你在上個學期用功一些，你就會在考試中過關了。

　　⑼、 If you had taken my advice, you wouldn't have failed in the exam.(從句動詞用had taken, 主句動詞用have failed)如果你當時聽從我的勸告的話，你就不會在考試中失敗了。

　　⑽、 If you had got up earlier, you could have caught the train.(從句動詞用had got up, 主句動詞用have caught)如果你起身得早一點，你就會趕得上火車了。

　　⑾、 If it had snowed, I would have skied in the park.(從句動詞用had snowed, 主句動詞用have skied)如果下雪的話，我就可在公園里滑雪了。

　　注意：如果動作在進行中，主句要用："主語+ would + have + 完成進行式動詞 +……

　　⑿、 If they had been here, he would have been speaking to them.(從句動詞用had been, 主句動詞用have been speaking)

　　(三)、表示與將來事實相反的虛擬條件句(對將來的事實實現的可能性不大)。其句子結構為：

　　從句：If + 主語+ should (或were) + 動詞原形+……

　　主句：主語+ would (could, should, might) + 動詞原形+……

　　例如：

　　⑴、If I were to work at this problem, I would do it in another way.要是我來解這道難題，我會用另外一種方法的。

　　⑵、If you were to do such a thing again, you would be punished. 如果你再做這樣的事情，就會受到懲罰。

　　⑶、If I should work harder, I could make much more progress.假如我更努力學習的話，我會取得更大的進步。(事實上我不可能努力學習)

　　⑷、If it should rain tomorrow, I would stay at home.如果明天下雨的話，我將待在家里。(根據天氣情況，明天不可能下雨)

　　⑸、If he should come, I could ask him for some advice.萬一他來了，我就能夠向他請教。(事實上他來的可能性很小)

　　⑹、If he came tomorrow, I would do it with him.如果明天他來的話，我將和他一起做此事。(事實上他來的可能性很小)

　　⑺、 If it should rain, the crops would be saved.(從句動詞用should rain，主句動詞用be)如果天下雨，莊稼可能就收獲了。

　　⑻、 If he were to go fomorrow, he might tell you.(從句動詞用were to, 主句動詞用tell)如果明天他走的話，他可能會告訴你。

　　⑼、 If he were here, I would give him the books.(從句動詞用were, 主句動詞用give)如果他在這兒，我可能會把書給他。

　　注意：如果動作在進行中，從句(不是主句喔)要用："If + 主語+ 過去進行式動詞 +……"

　　⑽、 If she were staying here now, I would let her ride my horse.(從句動詞用were staying, 主句動詞用let)如果她現在留在這兒，我可能會讓她騎我的馬。