1. 不知道動作的執(zhí)行者是誰，或沒有必要指出動作的執(zhí)行者時。如：
The glass is broken. 玻璃杯破了。
Letters are collected at eight every morning. 信件每天早晨八點收取。
2. 為了強調(diào)或突出動作的承受者時。如：
The desk was made by Master Wang. 這張課桌是王師傅做的。
The bag was taken away by his sister. 那個口袋是她姐姐提走的。
3. 在上下文中，為了使句子間連接緊密時。如：
I have a new motorbike. It was given to me as a birthday present by my father. 我有輛新摩托車。它是父親送給我作為生日禮物的。
4. 在新聞報道中，為了表明報道的客觀性而避免主觀性的透露時。如：
A car accident happened on the high way this morning. Three men were killed, the wounded were taken away to hospital at once and policemen were sent there to cope with the event. 今天早晨高速公路上發(fā)生了一起車禍，三人喪生，傷員馬上被送往了醫(yī)院，并馬上派了警察去處理這一事件。
5. 在科技論文中，常使用被動語態(tài)來強調(diào)客觀事實。如：
When it is cold enough, water will be turned into ice. 當天氣足夠冷時，水就會變成冰。
So far, the moon has been visited by earthmen several times. 到目前為止，地球人已經(jīng)幾次拜訪了月亮。
