since、 before、 ago 他们的区别是什么

since、 before、 ago 他们的区别是什么 for yet ago before since分别用于什么时态 Tom has lived in Shanghai____three years ago.A for B.since C.before D./ he start learning english since three years____.A.before B.ago It all happened a long time ____.A,before B,ago C,for D,since He told us that he had worked here since 10years before.这个句子对么?在此处since和before连用怎么讲?since 10years before完全等于since 10 years ago么？ The work has lived here for twenty years_____ A,since twenty years ago B.since he came hereC.twenty years ago D.twenty years before 为啥啊 The worker has lived here fortwenty years______ A,since twenty years ago B,since he came hereC,twenty years ago D.twenty years before since long ago 在英语中before与since与for与ago在时态的不同?用在什么时态?在英语中before,since,for,ago在用在什么时态?怎么用?回答时请举简单例子,不要太长篇大论, He has been in china ______.He loves chinese very much.A.for 2 years ago B.since 2 years ago C.for 2 years before D.since 2 years before 选哪一个,其他选项错在哪里了? He said,'I have been here since two years ago'把这个句子变成间接引语怎么变?是不是要把since two years ago变成since two years before? they have been here ___ two hours ago.A.for B.since C.before D.after 说明理由 How many years have you worked here?____ten years ago.为什么不能用Before而要用since? harry is leaving .he has been here since a month ()A.before B,later C.ago D.ahead 求理由 She left school three years ago and has worked as a nurse ever since.ago能换成before吗?ago是以过去的时间为标准,而这道题是用现在的时间为标准,符合before 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 it was i met miss white in hangzhou A:three years before B:three years ago that C:three years whenD:three years ago since