A for与表示一段时间的短语连用:
for six days六天
for a long time很久
for与一般过去时连用,表示一段终结了的时间:
We lived there for ten years.
我们在那里住过十年。(但我们现在不住那里了)
for与现在完成时连用表示延续到现在的一段时间:
We have lived in London for ten years.
我们在伦敦已经住了十年。(并且还住在那里)
for有时可以省略,特别是在be,live和wait之后:
Weve been here an hour/two days.
我们在这里已经呆了一小时/两天了。
表示时间的for不能用于以all开头的短语的前面:
Theyve worked all night.
他们整整干了一晚上。
B since与某一时刻连用,表示从那一时刻到说话时为止。除下文D与第188节所述外,它总是与完成时态连用。
She has been here since six oclock.
从6点钟起她一直在这里。(并且现在还在这里)
Weve been friends since our schooldays.
从上学的时候起我们就是好朋友了。
C注意:last和 the last之间存在着差别。
比较:
(a)I have been here since last week(month, year etc.).
我从上周(上月、去年等)起一直在这里。
(b)I have been here for the last week.
过去一周内我一直在这里。
第一句里last week意指大约七天前的某一时刻,而第二句的the last week却意指刚刚结束的七天长的时间。
D since+从句也可表示相同的意思:
Ive worked here since I left school.
离开学校后我就一直在这里工作。
ever since作副词用:
He had a bad fall last year and has been off work ever since.
他去年摔伤了,从那以后就没工作过。
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