by the time of 12,Edison (had began) to make money by himself.此处为何用过去完成时?
问题描述:
by the time of 12,Edison (had began) to make money by himself.此处为何用过去完成时?
题意为到他12岁时,并不是说他12岁前啊,如果12岁前才应该用过去完成时啊,想不通啊
答
by此处意思是“到.为止”,所以当它后面接一个过去的时间时,句子要用过去完成时