WhenItalkedwithmygrandmaonthephone,shesoundedweak,butbythetimewe（hung）up,hervoicehadbeenfulloflife,Bythetimeherealizeshe（haswalked）intoatrap,itwillbetoolate.这两句话同样是bythetime,为什么括号中

Question

When I talked with my grandma on the phone,she sounded weak,but by the time we（hung）up,her voice had been full of life,
By the time he realizes he（has walked）into a trap,it will be too late.这两句话同样是by the time,为什么括号中不一样,为什么第二句不遵循“主句过去完成时,从句一般现在时”.

Answer 1

by the time we（hung）up,her voice had been full of life.这后半句遵循过去完成时与过去时的搭配.第二句现在完成时强调对现在的影响.大概就是这个意思