1. since/s?ns/prep.& conj. 自從，自從…以來 +時(shí)間點(diǎn)或從句 ，表示動(dòng)作是什么時(shí)候開始得

前面得謂語動(dòng)詞或主句得謂語動(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+ 一般過去時(shí)得時(shí)間狀語從句 連詞

I haven’t seen him since I left that factory.我自從離開那家工廠還沒見過他

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+過去得時(shí)間點(diǎn)

=since+一般過去時(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.既然你同意我得觀點(diǎn)，讓我們一起開始吧。

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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(一般過去時(shí))

= 一段時(shí)間+has passed +since + 句子(一般過去時(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.從那以后我沒見過他。

He has written more than 10 books since then.從那以后他寫了十多本書

I haven't heard from her since then.從那以后，我沒有收到地得來信。

We have been good friends since then.從那時(shí)起我們就成為好朋友。