since...ago加完成时态吗?完成时态的标志是什么?

since...ago加完成时态吗?完成时态的标志是什么? since.ago能否用于现在完成时态 在现在完成时态 since 引导的句子中,主句的谓语动词必须用持续动词吗?He has left here since two years ago.He has been away since two years ago.是两个都对,还是有错? 完成时态for后加那些词,since后加那些词,要具体的,越多越好 since后面什么时候跟完成时态,什么时候用过去时态? 关于完成时态的!He said that he had met her two years.A.before B.ago C.for 2 years D.since 2 years ago She has swum since half an hour ago.不是说ago不能用在完成时吗? His grandpa died three years ago 改为现在完成时态 现在完成时态中,短暂性动词能与since引导的时间连用吗 He wrote the letter last week and posted it three days ago.改成一般现在时态和现在完成时态.要加时间状语! since before ,since ago 语法解析1 请问 在现在完成时态里面 since 5 years before ,since 5 years ago 那个对?还是都正确,讲解下.2 写个句子The air conditioner was turned on 5 hours ago.The air conditioner has been turned on si since three years ago 句子要用在 现在完成里吗?We __B__ english since three years ago.A.learned B.have learned Tom has been in Paris since 2 years agoI have been here since five months ago.问：1.since+时间+ago 在句子里怎么翻译, this hause has been completed since 1991.这里可以用has been completed表示被动的完成时态吗? for+时间是什么时态的标志 过去式和完成时都表示吗?怎么区别for.时间 ago 是表示现在完成时 那没有ago 表示什么 since years ago用于什么时态 since…ago表示什么时态 for和since的用法since时间后要加ago吗?还是for后加ago? 完成时加since的用法have 加延续动词pp 加since短语为从since开始动作的延续,而当动词为瞬间动词是则表示从since开始动作对现在的影响 这样说对么?I have lost my book since 1 year ago.I have been lost my bo