if三大虛擬語(yǔ)氣公式(if引導(dǎo)虛擬語(yǔ)氣三種時(shí)態(tài)表格)

虛擬語(yǔ)氣可以在狀語(yǔ)從句中表示讓步、方式和條件的句中出現(xiàn)，但他們體現(xiàn)的方式有所不同。這里談?wù)刬f引導(dǎo)的條件狀語(yǔ)從句中的虛擬語(yǔ)氣。

1.虛擬語(yǔ)氣用在條件狀語(yǔ)從句中表示與事實(shí)相反的假設(shè)。通常由連詞if來(lái)引導(dǎo)。在表示對(duì)將來(lái)的虛擬時(shí)有下列形式。

主句用would/should/could/might加動(dòng)詞原形，從句部分用should或者是were構(gòu)成。比如：

If you should need our help，you could tell us.如果你需要我們的幫助，請(qǐng)告訴我們。If it should happen，what would we do？如果發(fā)生的話(huà)，我們?cè)趺崔k？

2.當(dāng)虛擬條件句表示與現(xiàn)在事實(shí)相反時(shí)，它的形式是：主句用would/should/could/might+動(dòng)詞原形，從句部分用動(dòng)詞的過(guò)去式或were。比如：

If I were you, I’d finish it on time.如果我是你，我就按時(shí)完成。If I were a bird, I would fly away.如果我是只鳥(niǎo)，我就飛走了。

3.當(dāng)虛擬語(yǔ)氣表示對(duì)過(guò)去的假設(shè)時(shí)，句中的主句謂語(yǔ)用would/should/could/might+have+過(guò)去分詞，從句部分用had+過(guò)去分詞。比如：

I was so busy yesterday. If I had time, I would have called on you.我昨天太忙了。我要是有時(shí)間早就去看你了。

If we had got up earlier, we would have caught the train. 如果我們?cè)琰c(diǎn)起床，我們就趕上火車(chē)了。

4.從句中的連詞if可以省掉，但從句要部分倒裝。前提條件是：從句中謂語(yǔ)動(dòng)詞有were、had、should。這些詞可以提到從句最前面，也就是構(gòu)成了虛擬條件句的另一個(gè)句型。這也是虛擬語(yǔ)氣的考點(diǎn)之一。比如：

Were there no gravity, there would be no air around the earth.假如沒(méi)有重力，地球周?chē)蜎](méi)有空氣。

Were she in Beijing, she would help us.假如她在北京的話(huà)，她是會(huì)幫助我們的。

Had he time, he would help us to solve these problems.假如他有時(shí)間，他就會(huì)幫我們解決這些問(wèn)題了。

Should they come to us, I should ask them some questions.假如他們真能來(lái)我們這里的話(huà)，我將問(wèn)他們一些問(wèn)題。

Had the checking up of the experimental data not taken so much time, we should have completed our work long ago.假如檢驗(yàn)實(shí)驗(yàn)數(shù)據(jù)不花那么多時(shí)間，那末我們?cè)缇屯瓿蛇@項(xiàng)工作了。

Were it not for the leadership of the Party, we could not live a happy life.要不是黨的領(lǐng)導(dǎo)，我們不可能過(guò)幸福生活。