知識(shí)點(diǎn)：動(dòng)詞need,require,want作“需要”解,其后跟動(dòng)詞作它的賓語(yǔ)時(shí),若表示的含義是被動(dòng)的,必須用動(dòng)名詞,或不定式的被動(dòng)式。

例如：
The window needs(requires, wants)cleaning(to be cleaned).
在短語(yǔ)devote to, look forward to, pay attention to, stick to, be used to, object to,thank you for, excuse me for 等后的動(dòng)詞也必須用動(dòng)名詞形式：I look forward to hearing from you soon.
Badly polluted, the water cannot be drunk.(原因)
Being written in haste, the composition is full of mistakes.
(原因,強(qiáng)調(diào)寫(xiě)的過(guò)程,故應(yīng)用現(xiàn)在分詞一般被動(dòng)式)
Having been deserted by his guide, he couldn't find his way through the jungle.(為了強(qiáng)調(diào)已完成的動(dòng)作)
Asked to stay, I couldn't very well refuse.
這里 asked 可能意味著 having been asked, 也可能意味著when/since I was asked, 但用了 having been asked 就不會(huì)有歧義。
下面句中過(guò)去分詞表示的時(shí)間與謂語(yǔ)動(dòng)詞所表示的時(shí)間相同，所以不能代之以強(qiáng)調(diào)先于謂語(yǔ)動(dòng)詞的現(xiàn)在分詞完成被動(dòng)式。例如：
Covered with confusion, I left the room.我很窘地離開(kāi)了房間。
United, we stand; divided, we fall. 團(tuán)結(jié)則存，分裂則亡。
He used to live in London, use(d)n't he /didn't he?
There used to be a cinema here before the war, use(d)n't there /didn't there?
Such things ought not to be allowed, ought they?
He ought to be punished, oughtn't he?
但在正式文體中,用ought we not形式。例如:
We ought to go, ought we not?或We ought to go ,should we not?
動(dòng)詞need,require,want后跟動(dòng)詞作賓語(yǔ)時(shí)若表被動(dòng)則必用動(dòng)名詞,或不定式