If I had V-ed, I would have ...
    結(jié)構(gòu)┱If…h(huán)ad+過去分詞…，主詞+would/should 等+have+過去分詞
    說明┱這是與過去事實(shí)相反的假設(shè)。if 要用，則要用過去式(would，should，ought to，might，could)+have+過去。if 中的 had可置于前面，而省略 If。
    If I had seen him, I would have told him the truth. 如果我當(dāng)時(shí)看見他，我會告訴他實(shí)情。
    I could have finished the task if I had had more time.
    如果當(dāng)時(shí)我能有多一點(diǎn)時(shí)間，我就能完成這項(xiàng)任務(wù)。
    If we had known of your departure, we would have seen you off at the airport.
    如果我們事先知道你要離開，我們會到機(jī)場送行。
    I someone had been with him, he might not have been drowned.
    如果有人在他旁邊，或許他就不會溺死。
    I might have been incredulous had I not been accustomed to such responses.
    若非我已經(jīng)習(xí)慣了這樣的回答，我可能不敢輕易相信。
    Had he not apologize to her, she would not have forgiven him.
    她(那時(shí))不會原諒他，若非他道了歉。
    Had he not saved me, I might have been drowned. 我可能溺死了，若非他救了我。
    Had I proposed to you, would you have married me?
    我要是當(dāng)年向你求婚，你會答應(yīng)嫁給我嗎?
    Had you not helped us, we should have canceled this transaction.
    假如沒有你的幫助，這筆生意早就告吹了。
    If I had V-ed, I would ...
    結(jié)構(gòu)┱If…h(huán)ad+過去分詞…，主詞+would/should 等+原形動(dòng)詞+now/today
    說明┱這是不一致時(shí)的假設(shè)，亦稱混合假設(shè)條件句。即：if 若與過去事實(shí)相反，用表示;而若與現(xiàn)在事實(shí)相反，則用過去式表示。此類句尾通常有表現(xiàn)在的，如 now，today 等。
    If he had worked harder when young, he would be well off now.
    如果他年輕時(shí)多努力一點(diǎn)，現(xiàn)在就能過得舒服些。
    If I had been rich ten years ago, I could buy that house today.
    如果十年前我有錢，今天我就能買下那棟房子了。
    Had he told the truth, he wouldn’t be punished now.如果他當(dāng)時(shí)肯說實(shí)話，現(xiàn)在就不會受罪了。
    Had he followed the doctor’s advice, he might be alive now.
    當(dāng)時(shí)他要是聽了醫(yī)生的建議，現(xiàn)在可能還活著。