1.一般过去时,用来叙述过去发生的事情.如: I visited my grandparents yesterday. 2.现在完成时,表示过去发生的动作对现在的影响或造成的结果. I have learned English for five years. 3.过去完成时是一种相对的时态,它必须有另一动作或时间与之相对照才可使用.如:When I got to the station, the bus had already gone. 4.过去进行时,指在过去某一时刻正在发生的某事,如:I was writing a report when you called me yesterday morning.
记得采纳啊