Since的用法

　　一.Since作為介詞,后接某一確定的時(shí)間點(diǎn),主句謂語動(dòng)詞是持續(xù)性動(dòng)詞,常與現(xiàn)在完成時(shí)態(tài)、現(xiàn)在完成進(jìn)行時(shí)態(tài)或過去完成時(shí)態(tài)連用.例如：

　　1.She’s been working in a bank since leaving school.她中學(xué)畢業(yè)后就一直在一家銀行工作.

　　2.He had spoken to her only once since the party.自從那次聚會(huì)以來,他只跟她說過一次話.

　　3.He left the village in 1982 and I haven’t seen him since then.1982年他離開這個(gè)村子,從那以后我再?zèng)]見過他.

　　二.Since作為副詞,表示從過去以來、以后或到現(xiàn)在的情形或狀態(tài),常與現(xiàn)在完成時(shí)態(tài)連用.例如：

　　1.He came to Zhenjiang 6 years ago and has lived here (ever) since.他6年前來到鎮(zhèn)江,從此便住在這里.

　　2.He left home two weeks ago and we haven’t heard from him since.他兩周前離開了家,到現(xiàn)在我們一直沒有他的消息.

　　三.since引導(dǎo)原因狀語從句

　　作為連詞,since可引導(dǎo)原因狀語從句,表示因?yàn)?既然;鑒于：例如：

　　1. He didn’t come since he was busy.他因?yàn)槊?所以沒有來.

　　2. Since this method doesn’t work,let’s try another.既然這種方法不行,我們就試用另一種吧.

　　四.Since引導(dǎo)時(shí)間狀語從句

　　1.若since引導(dǎo)的狀語從句的謂語是終止性動(dòng)詞的過去時(shí),則從句表示的時(shí)間是“從動(dòng)作開始的那一時(shí)刻起”.例如：

　　He has studied very hard since he came to our school.自從他來到我們學(xué)校,他學(xué)習(xí)就非常努力.

　　We have been missing them since they left here自從他們離開這里,我們就一直很想念他們.

　　2.若since引導(dǎo)的狀語從句的謂語動(dòng)詞是持續(xù)性動(dòng)詞或表示狀態(tài)動(dòng)詞的過去時(shí)時(shí),則從句表示的時(shí)間是“從動(dòng)作或狀態(tài)結(jié)束時(shí)算起”.例如：

　　I haven’t heard any noise since I slept.Sleep 為持續(xù)性動(dòng)詞,sleep的動(dòng)作結(jié)束時(shí),即“醒來”時(shí),所以這句應(yīng)譯為“我醒后還未聽到任何聲音”.

　　3.若since引導(dǎo)的狀語從句的謂語為持續(xù)性動(dòng)詞的現(xiàn)在完成時(shí),則表示動(dòng)作和狀態(tài)延續(xù)到現(xiàn)在(說話時(shí)刻),其表示的時(shí)間的起點(diǎn)應(yīng)從動(dòng)作發(fā)生之時(shí)算起.例如：I haven’t heard from him since he has lived there.這里has lived表示動(dòng)作的持續(xù)性,時(shí)間的起點(diǎn)應(yīng)從：“開始居住”時(shí)算起.因此此句可理解為“自從他(開始)住在那兒起,我就一直沒收到他的來信”.

　　五.Since在特殊句型中的應(yīng)用

　　句型I：“It is (has been)+時(shí)間+since+持續(xù)性動(dòng)詞的過去時(shí)”,表示“自從……以來到現(xiàn)在已有多久.”例如：

　　It has been quite some time since I was last in London.我上次離開倫敦至今頗有一段時(shí)間了.

　　句型II：“It was+時(shí)間+since+持續(xù)性動(dòng)詞的過去完成時(shí)”,表示“從……到過去某時(shí)間點(diǎn)以來”,例如：It was three years since we had been here.那時(shí)我們在這已呆了三年.