By the time by the end of

1。表示将来的时间。
主句用将来完成时,而从句用一般现在时来表示将来的动作。
如:I will have finishied the work by the time my father comes back。
2。表示过去的时间。
主句用过去完成时,而从句用一般过去时。
如：He had built a lab for himself by the time he was 12 years old。
by the end of
“到。末”,多指时间,常用于完成时态,也用于将来时态。By the end of last month they had planted 10,000 trees。到上个月月底他们已经栽了一万棵树。The population of this town will be 1,500,000 by the end of 2010。到2010年年底这个城镇的人口将有一百五十万。