1. since/s?ns/prep.& conj. 自從，自從…以來(lái) +時(shí)間點(diǎn)或從句 ，表示動(dòng)作是什么時(shí)候開(kāi)始得
前面得謂語(yǔ)動(dòng)詞或主句得謂語(yǔ)動(dòng)詞必須用完成時(shí)，要用延續(xù)性動(dòng)詞。
①since+時(shí)間點(diǎn) 介詞
since last week since 2009
I have been here since 2009.
He has stayed here since 5 o’clock.
I have been living here since 2000.
I haven’t heard from him since last summer.
I got a headache since last night.我從昨晚開(kāi)給就一直頭痛。
They have lived in Beijing since 1980.他們自1980年就一直住在北京。
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②since+ 時(shí)間段+ ago
since 5 hours ago
He has stayed here since 5 hours ago.
③since+ 一般過(guò)去時(shí)得時(shí)間狀語(yǔ)從句 連詞
I haven’t seen him since I left that factory.我自從離開(kāi)那家工廠(chǎng)還沒(méi)見(jiàn)過(guò)他
We’ve known each other since we were children.我們從小就認(rèn)識(shí)。
I have been here since I graduated in 2000.
She has taught English since he came here.
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since+過(guò)去得時(shí)間點(diǎn)
=since+一般過(guò)去時(shí)得句子
=for+時(shí)間段
She has lived here for ten years.
=She has lived here since ten years ago. 她已經(jīng)在這里住了十年了。
I have lived here since two years ago.
=I have lived here for two years.我住在這兒兩年了
I’ve lived here for 15 years.
=I’ve lived here since 15 years ago.
I have been here for 5 years.
=I have been here since 5 years ago.
He has been away since last week.
=He has been away for one week.
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2.既然；因?yàn)?/p>
Since you agree with me, let’s start together.既然你同意我得觀(guān)點(diǎn)，讓我們一起開(kāi)始吧。
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3.since 也可單獨(dú)使用, 自那時(shí)起; since前也可加上ever,加強(qiáng)語(yǔ)氣.
I have been here (ever) since.
I have been here (ever) since I graduated in 2000.
It is +一段時(shí)間+since+句子(一般過(guò)去時(shí))
= 一段時(shí)間+has passed +since + 句子(一般過(guò)去時(shí))
It is five years since I joined the army.
=Five years has passed since I joined the army.
since then從那以后，句子常用現(xiàn)在完成時(shí)，且句中得動(dòng)詞應(yīng)用延續(xù)性動(dòng)詞，如果為非延續(xù)性動(dòng)詞必須把它轉(zhuǎn)換為延續(xù)性動(dòng)詞。
I have not seen him since then.從那以后我沒(méi)見(jiàn)過(guò)他。
He has written more than 10 books since then.從那以后他寫(xiě)了十多本書(shū)
I haven't heard from her since then.從那以后，我沒(méi)有收到地得來(lái)信。
We have been good friends since then.從那時(shí)起我們就成為好朋友。
