1) 用于完成時(shí)的區(qū)別
延續(xù)動(dòng)詞表示經(jīng)驗(yàn)、經(jīng)歷； 瞬間動(dòng)詞表示行為的結(jié) 果，不能與表示段的時(shí)間狀語(yǔ)連用。
He has completed the work. 他已完成了那項(xiàng)工作。 (表結(jié)果)
I've known him since then. 我從那時(shí)起就認(rèn)識(shí)他了。(表經(jīng)歷)
2) 用于till / until從句的差異
延續(xù)動(dòng)詞用于肯定句，表示"做……直到……" 瞬間動(dòng)詞用于否定句，表示"到……，才……"
He didn't come back until ten o'clock.
他到10 點(diǎn)才回來(lái)。
He slept until ten o'clock.
他一直睡到10點(diǎn)。
典型例題
1. You don't need to describe her. I ___ her several times.
A. had met B. have met C. met D. meet
答案B. 首先本題后句強(qiáng)調(diào)對(duì)現(xiàn)在的影響，我知道她的模樣，你不用描述。再次，several times告知為反復(fù)發(fā)生的動(dòng)作，因此用現(xiàn)在完成時(shí)。
2.---I'm sorry to keep you waiting.
---Oh, not at all. I ___ here only a few minutes.
A. have been B. had been C. was D. will be
答案A. 等待的動(dòng)作由過(guò)去開(kāi)始，持續(xù)到現(xiàn)在，應(yīng)用現(xiàn)在完成時(shí)。
since的四種用法
1) since +過(guò)去一個(gè)時(shí)間點(diǎn) (如具體的年、月、日期、鐘點(diǎn)、1980, last month, half past six)。
I have been here since 1989.
2) since +一段時(shí)間+ ago
I have been here since five months ago.
3) since +從句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
4) It is +一段時(shí)間+ since從句
It is two years since I became a postgraduate student.
延續(xù)動(dòng)詞表示經(jīng)驗(yàn)、經(jīng)歷； 瞬間動(dòng)詞表示行為的結(jié) 果，不能與表示段的時(shí)間狀語(yǔ)連用。
He has completed the work. 他已完成了那項(xiàng)工作。 (表結(jié)果)
I've known him since then. 我從那時(shí)起就認(rèn)識(shí)他了。(表經(jīng)歷)
2) 用于till / until從句的差異
延續(xù)動(dòng)詞用于肯定句，表示"做……直到……" 瞬間動(dòng)詞用于否定句，表示"到……，才……"
He didn't come back until ten o'clock.
他到10 點(diǎn)才回來(lái)。
He slept until ten o'clock.
他一直睡到10點(diǎn)。
典型例題
1. You don't need to describe her. I ___ her several times.
A. had met B. have met C. met D. meet
答案B. 首先本題后句強(qiáng)調(diào)對(duì)現(xiàn)在的影響，我知道她的模樣，你不用描述。再次，several times告知為反復(fù)發(fā)生的動(dòng)作，因此用現(xiàn)在完成時(shí)。
2.---I'm sorry to keep you waiting.
---Oh, not at all. I ___ here only a few minutes.
A. have been B. had been C. was D. will be
答案A. 等待的動(dòng)作由過(guò)去開(kāi)始，持續(xù)到現(xiàn)在，應(yīng)用現(xiàn)在完成時(shí)。
since的四種用法
1) since +過(guò)去一個(gè)時(shí)間點(diǎn) (如具體的年、月、日期、鐘點(diǎn)、1980, last month, half past six)。
I have been here since 1989.
2) since +一段時(shí)間+ ago
I have been here since five months ago.
3) since +從句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
4) It is +一段時(shí)間+ since從句
It is two years since I became a postgraduate student.