He offered me a drink before I had taken off my coat. He arrived before I had finished my lunch. Note:能同时使用两个过去完成时的场合极少，下面带有由 by the time引导的时间状语分句的句子是少数例外中 的一个： By the time I(had)recovered from the shock,he had disappeared. C)Use of present perfective progressive The use of the present perfective progressive (have/has been +-ing participle)has much in common with the"unfinished"use of the present perfective.Compare: I've been writing letters for an hour(and I've still got some more to do). 6
6 He offered me a drink before I had taken off my coat. He arrived before I had finished my lunch. Note: 能同时使用两个过去完成时的场合极少,下面带有由 by the time 引导的时间状语分句的句子是少数例外中 的一个: By the time I(had) recovered from the shock,he had disappeared. C) Use of present perfective progressive The use of the present perfective progressive (have / has been + -ing participle) has much in common with the “unfinished” use of the present perfective. Compare: I’ve been writing letters for an hour ( and I’ve still got some more to do)
I've been sitting in the garden(and have just come indoors). In many cases these two forms can be used interchangeably: We've been living here for ten years. We've lived here for ten years. There are cases,however,where these two forms are not interchangeable in that the present perfective progressive has also the meanings of continuousness and incompleteness.Compare: Who's been eating my dinner?(Some of it is left.") Who's eaten my dinner?(It's all gone.")
7 I’ve been sitting in the garden ( and have just come indoors). In many cases these two forms can be used interchangeably: We’ve been living here for ten years. We’ve lived here for ten years. There are cases, however, where these two forms are not interchangeable in that the present perfective progressive has also the meanings of continuousness and incompleteness. Compare: Who’s been eating my dinner? (“Some of it is left.”) Who’s eaten my dinner? (“It’s all gone.”)
Uses of past perfective progressive The past perfective progressive (had been +-ing participle)is basically similar in use of the present perfective progressive,only with time reference back-shifted to a specified past. The chief use of the past perfective progressive has also something in common with the unfinished"use of the past perfective,changeably, though in colloquial speech,the past perfective. Compare: I'd been working for three hours when he called.(collog.) I'd worked for three hours when he called. 8
8 D) Uses of past perfective progressive The past perfective progressive (had been + -ing participle) is basically similar in use of the present perfective progressive, only with time reference back-shifted to a specified past. The chief use of the past perfective progressive has also something in common with the “unfinished” use of the past perfective, changeably, though in colloquial speech, the past perfective. Compare: I’d been working for three hours when he called.(colloq.) I’d worked for three hours when he called
E)More on the use of perfective tense There are a few more points that merit our attention concerning the use of the perfective tense. a)perfective tense is often accompanied by a since-phrase or a since-clause to denote a continuous state or activity from a point in past time until now.The verb in the since clause is commonly the simple past of a dynamic verb denoting non-continuous activity. If the main or super-ordinate clause is in the
9 E) More on the use of perfective tense There are a few more points that merit our attention concerning the use of the perfective tense. a) perfective tense is often accompanied by a since-phrase or a since-clause to denote a continuous state or activity from a point in past time until now. The verb in the sinceclause is commonly the simple past of a dynamic verb denoting non-continuous activity. If the main or super-ordinate clause is in the
form ofIt be complement (denoting a time span)+since-clause",the verb be in the main clause may occur in the simple present in place of the present perfective,eg: I haven't seen him since his wedding day/since I met you. It's three months since he wrote to me. Sometimes,however,the verb in the since- clause may be the simple past of a dynamic stative(状态动词)verb,in which case the time span denoted by the since-clause is different from the present moment,we will have to use the present perfective instead of the simple past.Compare: 10
10 form of “It be + complement (denoting a time span) + since-clause”, the verb be in the main clause may occur in the simple present in place of the present perfective, eg: I haven’t seen him since his wedding day/ since I met you. It’s three months since he wrote to me. Sometimes, however, the verb in the sinceclause may be the simple past of a dynamic stative（状态动词） verb, in which case the time span denoted by the since- clause is different from the present moment, we will have to use the present perfective instead of the simple past. Compare: