had改為has,這里用完成時(shí),不是過去完成時(shí).
could不代表過去,只表示虛心提問對(duì)方為什么不能用過去完成時(shí)，表他以前走了多長時(shí)間那豈不是所有“過去的動(dòng)作”都要用過去完成時(shí)了？I had answered this question.I had walked for hours.I had read this book.I had finished it.I had used so many "had"s。。。。過去完成時(shí)表示過去的過去，這里用完成時(shí)就行了。