完成時中的延續(xù)性用法和非延續(xù)性用法.終止性動詞和延續(xù)性動詞.
例：
誤：She has caught a bad cold for a week.
正：She has had a bad cold for a week.
這里catch是終止性動詞,have是持續(xù)性動詞.終止性動詞在現(xiàn)在完成時的肯定句里,不能用表示一段時間的狀語來修飾它們,也就是說不能用for短語(表示時間長度),或since短語詞(或從句),也不能用在how long引起的疑問句中.
若需要表示持續(xù)一段時間時,可以用下列兩種形式：1用It is(或has been)since句型；2用副詞ago把句子改為一般過去時.如：
誤：The American musician has arrived here for about a month.
正：It is(或has been)about a month since the American musician arrived here.
正：The American musician arrived here about month ago.
除了改變句型結(jié)構(gòu)外,還可對動詞作相應(yīng)變化.其中多數(shù)終止性動詞可用be來表示延續(xù),有些可用相應(yīng)的延續(xù)性動詞來代替.如：
誤：My sister had joined the Party for over six years.
正：My sister has been a Party member for over six years.
誤：How long have you borrowed the book?
正：How long have you kept the book?
常用的替換詞有：come be here,leave be away,die dead,begin be on,open be open,become be,buy have,borrow keep,eat have,join be in,(或be a member of),get up be up,get ready be ready,get to know know,make friends be friends,go to bed sleep,catch a cold have a cold等.
需要注意的是：
1、在否定句中,終止性動詞可以轉(zhuǎn)化為延續(xù)性的否定狀態(tài),因此可以和表示一段時間的狀語連用.如：
I haven’t heard from my brother for many years.
The rain hasn’t stopped since three minutes ago.
2、終止性動詞可以用于“表示過去發(fā)生的某一動作對現(xiàn)在造成的影響或結(jié)果”這種概念的現(xiàn)在完成時中,說明某個動作的結(jié)果還存在,不跟表示一段時間的狀語連用,但可用already,yet,before,just,ever,now,today等時間狀語.如：
I have already posted the photos.
Have you seen the film before?