since在现在完成时的用法是什么?

since在现在完成时的用法是什么?

since在现在完成时里一般是用来引导时间状语，而且时态多是一般过去时。
不知道是不是你要问的，如果是的话望采纳，谢谢。

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)。 i have been here since 1989. 2) since +一段时间+ ago i have been here since five months ago. 3) since +从句 great changes have taken place since you left. considerable time has elapsed since we have been here. 4) it is +一段时间+ since从句 it is two years since i became a postgraduate student. 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。 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 作为延续动词一般用于肯定句，表示"做……直到……" 作为瞬间动词一般用于否定句，表示"到……，才……" he didn't come back until ten o'clock. 他到10 点才回来。 he slept tll ten o'clock. 他一直睡到10点。 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。 1．写出下列单词的过去式、过去分词 arrive _________ _________ brush _________ __________ send _________ _________ write _________ __________ hear _________ __________ fall _________ __________ drop_________ __________ lose _________ __________ feel _________ __________ lose__________ __________ use _________ __________ wear _________ _________ think________ __________ thank_________ _________ own _________ __________ invent ________ _________ build _________ _________ allow _________ __________ 2. 用单词的适当形式填空 1).- _____ you ______(write )your letter yet ? – yes, i _______ (write ) it last night . 2)- jim ____________ ( not finish ) his homework yet .when _______ he ________(finish ) it? - maybe tomorrow . 3) -i ________ never _______ (be) to america before . what about you ? -i _________ (go) there last year . 4) –where is your father ? -he _______ (go ) to beijing . he ________ (leave ) five days ago . 5)-i’m sorry to keep you waiting here. -oh, it doesn’t matter . i ________ (be) here for only a few minutes . 6) we will wait here until another bus _______ (come ) . 7) –have you finished your homework ,tom ? – not yet . i _________ (do) it now . 8)- when ______ you ______ (plant ) the tree ? – last year. 9) i don’t know if mary ________ (come) .if she _______ (come), i’ll tell her what to do . 10)- _____ you _____ (go) and ______ (see) a film with me tonight ? -no, i won’t . i _______ (see) it already . 11) we ______ (hold) a meeting yesterday . and there ________ (be) another one tomorrow . 12)- who _____ (win ) the men’s football match ? – we did . 13) the students of grade three ________ (learn) more than 2000 english words so far . 14)- how long _____ your grandfather _____ (be ) dead ? – for two years . he ______ (die ) the year before last . 15)- _____ you _____ (read ) this book before ? –yes ,i ______ (read ) twice . 16) it ______ (be) five days since he ______ (leave ) his hometown . 17) i ______ (wait )you for a long time . where _____you _____ ( be) ? 18) all the children _______ (enjoy )themselves now .some ______ (sing ) , some ______ (dance ), others _______ (play ) games . 19) china _______ (send ) many man-made satellites into the space in the last three years . 20) when i ______ (leave ) school a moment ago ,it ________ (rain ) hard . 21) don’t watch tv until your homework ________ (do) . 22) he ________just ______ (travel) to foreign countries . 23) we _________ ( not see) each other since we ________ ( leave ) middle school. 24) while i _______ (walk) on the road last night , i ______ (meet) an old friend of mine . 25)- ______ your mother ever______ (watch) such a film ? – no, never. 3.转变句型 1） he joined the army two years ago . he ______ ______ ______ the army _____ two years . 2） the man bought a new car last month . the man ______ ______ a new car ______ last month . 3） the baby fell asleep five minutes ago . the baby _______ ______ asleep _____ five minutes . 4） they opened the shop last week . the shop ______ ______ _______ for a week . 5） tom borrowed the books yesterday . tom ______ ______ the books for only one day . 6） the film began half an hour ago . the film ______ _______ ______ for half an hour . 7） she became a league member last year . she _____ ______ a league member _____ last year. 8） the girl left her hometown ten years ago . the girl _____ _____ ____ _____her hometown for ten years . 9） i got to know him three years ago . i_____ _____ him ______ three years . 10） we began to learn english two years ago . we ____ ____ english ____ two years ago