完成體是動詞的一種形式，表示動作或狀態(tài)已經(jīng)完成，結(jié)構(gòu)是：主動詞have的不同時態(tài)+-ed分詞?？梢苑譃楝F(xiàn)在完成體和過去完成體?，F(xiàn)在完成體大家比較熟悉了，那么今天小編就和大家一起學(xué)習(xí)我們不太熟悉的過去完成體~

過去完成體，顧名思義，就是表示在過去某一時間之前已經(jīng)發(fā)生或完成的動作，也就是我們所說的“過去的過去”。因此，它有“已完成”用法和“未完成”用法。結(jié)構(gòu)為：had+-ed分詞。

一、“已完成”：表示一個動作或狀態(tài)在過去某時之前已經(jīng)完成或結(jié)束。

I had finished my homework when my friends came.我朋友來的時候，我就已經(jīng)完成家庭作業(yè)了。

My father had left for Beijing before I came home. 在我到家前，爸爸已經(jīng)離開去北京了。

二、“未完成”：表示一個動作或狀態(tài)在過去某時之前已經(jīng)開始，一直延續(xù)到這一過去時間，而且到那時還未結(jié)束，仍有繼續(xù)下去的可能性。

Jack said that he had made much progress in English since he came here.

杰克說自從他到這兒以后，英語已經(jīng)取得了很大進步。

By six o’clock these workers had worked twelve hours. 到六點鐘時，這些工人已經(jīng)工作十二小時了。

三、連詞引導(dǎo)過去完成體用法：有些連詞引導(dǎo)的過去完成時可互換。

??When I?reached the station, the train had already left.

=I reached the station after?the train had left.

=I didn’t reach the station?until the train had left.

=The train had left before I reached the station.

??在我到車站時，火車已經(jīng)走了。

四、過去完成體的虛擬用法：表示與過去事態(tài)相反的主觀設(shè)想。

1. 用于if, if only, as if引導(dǎo)的分句：

? If you had worked hard, you would have passed the exam. 如果你努力學(xué)習(xí)的話，你就已經(jīng)通過考試了。

? If I were you, I would not do it. 我要是你，就不做這事。

? If only I had finished it before. 要是我之前完成了這件事就好了。

? I felt as if I had been a bird in the sky.我感覺自己好似天空一只小鳥。

2. 用于I wish, I would rather引導(dǎo)的that從句：

???I wished that I had knew the answer to the question before he asked me. 我希望在他問我以前，我知道問題的答案。

? ?I would rather you had told me the truth. 我寧愿你跟我說實話。

3. 用于expect, think, intend, mean, want, suppose等表示過去未曾實現(xiàn)的希望、打算或意圖。

? I had intended to buy a present for you, but I forgot that. 我本打算給你買禮物的，但我忘了。

? I had hoped that we could pass the exam, but we failed in the end. 我本希望我們都能通過考試，但最終我們失敗了。

因此，由上可知，比起現(xiàn)在完成體，過去完成體用法復(fù)雜，且具體“虛擬”的特殊用法，需要我們在平時使用中加以注意。