[动词的时态]比较since和forSince 用来说明动作起始时间,for用来说明动作延续时间长度。例如:
I have lived here for more than twenty years.我住在这儿二十多年了。
I have lived here since I was born. 我从出生起就住在这儿了。
注意:并非有for 作为时间状语的句子都用现在完成时。
I worked here for more than twenty years. (我现在已不在这里工作。)
I have worked here for many years.(现在我仍在这里工作。)
注意:用句型转换的方法,很容易排除非延续动词在有for/since结构的完成时中的误用。
1)(对) Tom has studied Russian for three years. = Tom began to study Russian three years ago, and is still studying it now.
2)(错) Harry has got married for six years. = Harry began to get married six years ago, and is still getting married now.
显然,第二句不对,它应改为 Harry got married six years ago. 或 Harry has been married for six years.
[动词的时态]since的四种用法
1) since +过去一个时间点(如具体的年、月、日期、钟点、1980, last month, half past six)。例如:
I have been here since 1989. 1989起,我一直在这儿。
2) since +一段时间+ ago.例如:
I have been here since five months ago. 我在这儿,已经有五个月了。
3) since +从句。例如:
Great changes have taken place since you left. 你走后,变化可大了。
Great changes have taken place since we were here. 我们走后,变化可大了。
4) It is +一段时间+ since从句。例如:
It is two years since I became a postgraduate student. 我考上研究生有两年了。
[动词的时态]延续动词与瞬间动词
1) 用于完成时的区别
延续动词表示经验、经历; 瞬间动词表示行为的结果,不能与表示段的时间状语连用。例如:
He has completed the work. 他已完成了那项工作。 (表结果)
I've known him since then. 我从那时起就认识他了。(表经历)
2) 用于till / until从句的差异
延续动词用于肯定句,表示"做……直到……" 瞬间动词用于否定句,表示"到……,才……".例如:
He didn't come back until ten o'clock. 他到10 点才回来。
He slept until ten o'clock. 他一直睡到10点。
典型例题
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. 首先本题后句强调对现在的影响,我知道她的模样,你不用描述。再次,several times告知为反复发生的动作,因此用现在完成时。
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. 等待的动作由过去开始,持续到现在,应用现在完成时。
I have been here since 1989. 1989起,我一直在这儿。
2) since +一段时间+ ago.例如:
I have been here since five months ago. 我在这儿,已经有五个月了。
3) since +从句。例如:
Great changes have taken place since you left. 你走后,变化可大了。
Great changes have taken place since we were here. 我们走后,变化可大了。
4) It is +一段时间+ since从句。例如:
It is two years since I became a postgraduate student. 我考上研究生有两年了。
[动词的时态]延续动词与瞬间动词
1) 用于完成时的区别
延续动词表示经验、经历; 瞬间动词表示行为的结果,不能与表示段的时间状语连用。例如:
He has completed the work. 他已完成了那项工作。 (表结果)
I've known him since then. 我从那时起就认识他了。(表经历)
2) 用于till / until从句的差异
延续动词用于肯定句,表示"做……直到……" 瞬间动词用于否定句,表示"到……,才……".例如:
He didn't come back until ten o'clock. 他到10 点才回来。
He slept until ten o'clock. 他一直睡到10点。
典型例题
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. 首先本题后句强调对现在的影响,我知道她的模样,你不用描述。再次,several times告知为反复发生的动作,因此用现在完成时。
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. 等待的动作由过去开始,持续到现在,应用现在完成时。