1.现在完成时的动作虽发生在过去,但强调的是对现在造成的影响.
构成：have / has + 动词的过去分词
如:He has eaten the breakfast.他已经吃过早饭了.（强调现在不饿）
He has been to Beijing twice.他已经去过北京两次
I have lived in Beijing since I came to China.自从我来到中国就住在北京.
I have learned French for two years 同义句 I have learned French since two years ago.
构成现在完成时的时间状语：already,ever,never,yet,so far(到目前为止）,in the past/ last few years (在过去的几年间）,over the years （近年来）
2.过去完成时动作发生在过去的过去.He said he had been to Beijing twice.他说他已经去过北京两次.（因为“说”said就是过去式,而去北京的动作发生在说said 的过去,所以用过完而不用现完.
过去完成时常用的时间状语有 1.by the end of last year.
By the end of last term,we had learned 5000 new words.
2.By the time sb.+动词过去式 如：The bus had already left by the time I got there.
3.宾语从句
He went to Canada last month.他上个月去加拿大了.
He said he had been to Canada last month.他说他上个月去加拿大了.
主句谓语动词是过去式said ,从句谓动发生在过去的过去,所以用过去完成时
