課本中不會(huì)教你的[W]714　when，while，after，before，if+分詞等

714　when，while，after，before，if+分詞等

① when，while引導(dǎo)狀語(yǔ)從句時(shí)，如果從句的主語(yǔ)同主句的主語(yǔ)為同一人或物，從句中的主語(yǔ)及助動(dòng)詞be?？墒÷?，采用“從屬連詞+現(xiàn)在分詞、過(guò)去分詞或介詞短語(yǔ)等”結(jié)構(gòu)。

He met an old friend when walking along the road. 在路上走著時(shí)，他遇見(jiàn)了一位老朋友。（=When he was walking along the road）

Be careful when crossing the road. 過(guò)馬路時(shí)要當(dāng)心。

When reading the letter，she couldn't help crying. 閱讀這封信時(shí)，她不禁哭了起來(lái)。（=When she was reading the letter）

While talking in the room，they heard a strange sound outside. 在房間里說(shuō)話時(shí)，他們聽(tīng)見(jiàn)外面有一個(gè)奇怪的聲音。（=While they were talking in the room）

While doing so，he decided to buy a car. 他做這事時(shí)決定買(mǎi)一輛車(chē)。（=While he was doing so）

When in trouble，ask her for help. 遇到麻煩時(shí)就請(qǐng)她幫忙。（=When you are in trouble）

While in London he studied English very hard. 他在倫敦時(shí)努力學(xué)習(xí)英語(yǔ)。（=While he was in London）

② after和before引導(dǎo)時(shí)間狀語(yǔ)從句時(shí)，如果從句的主語(yǔ)同主句的主語(yǔ)為同一人或物，?？赊D(zhuǎn)換為“after、 before+現(xiàn)在分詞”結(jié)構(gòu)。

After going over the lessons，she went to bed. 她復(fù)習(xí)完功課后就睡了。（=After she went over the lessons）

After having worked for a whole day，he felt a bit tired. 工作了一整天之后，他感到有點(diǎn)累。

Before moving to Shanghai，she had lived in Hangzhou for twenty years. 在搬到上海之前，她已在杭州住了20年。（=Before she moved to Shanghai）

Before beginning to do his homework，he had watched TV half an hour. 在開(kāi)始做作業(yè)之前，他已看了半個(gè)小時(shí)的電視。（=Before he began to do his homework）

③ if引導(dǎo)的從句如果是被動(dòng)語(yǔ)態(tài)，而且從句的主語(yǔ)同主句的主語(yǔ)又相一致時(shí)，從句中的主語(yǔ)和be動(dòng)詞可省略，轉(zhuǎn)換為“if+過(guò)去分詞”結(jié)構(gòu)。

If given more time，I could do the work better. 如果給更多時(shí)間的話，這項(xiàng)工作我可以做得更好。

If given another chance，he may succeed. 如果再給一次機(jī)會(huì)的話，他可能會(huì)成功的。