过去完成时的被动语态

　　过去完成时：结构 had+been+done(V. p.p.)

　　主动：Somebody had cleaned my shoes.

　　被动：My shoes had been cleaned by somebody.

　　有人已把我的鞋子擦了。

　　主动：When I returned I found that they had towed (tow) my car away, I asked why they had done this and they told me that it was because I had parked it under a "No Parking Sign".

　　被动：My car had been towed away. I asked why this had been done and told that...it had been parked under a "No Parking Sign".

　　当我回来时，发现我的车被拖走了。我问他们为什么这么干。他们告诉我说因为我把车停在“禁止停车”的区域。

　　主动：They had build three ships by last December.

　　被动：By last December three ships had been built by them.

　　到去年年底他们已建造了三艘船。

　　Research had been centred on the improvement of natural building materials before synthetics were created.

　　合成材料造出之前，研究工作集中在改进天然建筑材料上。

　　He did not say if all those steel pipes had been examined.

　　他并没有说那些钢管是否都检验过。

　　After plastic had been created, engineers were given a much wide choice of materials.

　　塑料发明之后，工程师们在材料选择上有了更广阔的途径。