先看新概念英语中的这篇文章OnstrikeBusmenhavedecidedtogoonstrikenextweek.ThestrikeisduetobeginonTuesday.Nooneknowshowlongitwilllast.Thebusmenhavestatedthatthestrikewillcontinueuntilgeneralagreementis

Question

先看 新概念英语 中的这篇文章On strike
Busmen have decided to go on strike next week.The strike is due to begin on Tuesday .No one knows how long it will last.The busmen have stated that the strike will continue until general agreement is reached about pay and working conditions.Most people believe that the strike will last for at least a week.Many owners of private cars are going to offer 'free rides' to people on their way to work.This will relieve pressure on the trains to some extent.Meanwhile,a number of university students have volunteered to drive buses while the strike lasts.All thestudents are expert drivers,but before they drive any of the buses,they will have to pass a special test.The students are going to take the test in 2 days'time.Even so,people are going to find it difficult to get to work.But so far,the public has expressed its gratitude to the students in letters to the Press.Only one or two people have objected that the students will drive too fast.
我看了很多新概念里面的文章.以这篇文章为例,为什么里面不单单用现在式或过去式?而是经常用'have been'这种形式的?比如上面第四句"The busmen have stated that the strike will continue until general agreement is reached about pay and working conditions."为什么这一句要用have stated,而不是stated

Answer 1

你说的是现在完成时的问题
一般过去时的定义在过去某个时间发生的动作或存在的状态.一般所在的句子有很明确的过去时间状语,如yesterday,last week,two years ago
现在进行时的定义是指动作从过去某时候开始,持续到现在,也有可能会继续持续下去,强调对现在的影响.常用时间状语,recently,in the past years,since,yet等.
两者的区别具体包括,
1.现在完成强调过去的动作对现在的影响,一般过去只表示过去的某个具体时间里发生的动作,与现在没联系.
She left here five minutes ago.（就说明走了）
She has left.（强调现在不在这了）
2.现在完成表示动作从过去开始,可能还要延续下去.一般过去说明动作已结束.
He worked in the hospital for 5 years.(现在不在那工作了)
He has worked in the hospital for 5 years.（现在仍在）
3.时间状语上的区别.