1.現(xiàn)在完成時的動作雖發(fā)生在過去,但強調(diào)的是對現(xiàn)在造成的影響.
構(gòu)成：have / has + 動詞的過去分詞
如:He has eaten the breakfast.他已經(jīng)吃過早飯了.（強調(diào)現(xiàn)在不餓）
He has been to Beijing twice.他已經(jīng)去過北京兩次
I have lived in Beijing since I came to China.自從我來到中國就住在北京.
I have learned French for two years 同義句 I have learned French since two years ago.
構(gòu)成現(xiàn)在完成時的時間狀語：already,ever,never,yet,so far(到目前為止）,in the past/ last few years (在過去的幾年間）,over the years （近年來）
2.過去完成時動作發(fā)生在過去的過去.He said he had been to Beijing twice.他說他已經(jīng)去過北京兩次.（因為“說”said就是過去式,而去北京的動作發(fā)生在說said 的過去,所以用過完而不用現(xiàn)完.
過去完成時常用的時間狀語有 1.by the end of last year.
By the end of last term,we had learned 5000 new words.
2.By the time sb.+動詞過去式 如：The bus had already left by the time I got there.
3.賓語從句
He went to Canada last month.他上個月去加拿大了.
He said he had been to Canada last month.他說他上個月去加拿大了.
主句謂語動詞是過去式said ,從句謂動發(fā)生在過去的過去,所以用過去完成時