at the end与at the eng of和in the end、by the end of的区别说明一下再分别举个例子

没有at the end .但有at an end.
at an end 是指"结束了"的意思. eg:The work is at an end.这项工作结束了.
at the end of "在....的最后,在...的末尾" eg:The man was dead at the end of the stroy.在故事的结束,这个人死了.
in the end 是个短语,单独使用. eg:In the end, she gained nothing.
by the end of 首先,BY到"到...为止".所以by the end of 是到．．．的最后．是表示一下时间段．而at the end of 是个时间点．专指那一刻．
eg:He hadn't finished the homework by the end of the holiday.

at the age of 在..岁时

首先,应该没有 at the end 这样的搭配
然后,
1.in the end 和 at last 差不多,就是指 在最后,
They won in the end.最后他们赢了.
2.at he end of 是 在……的最后,
He could eat nothing at the end of his life.在他生命的最后日子他什么也吃不了了.
3.by the end of 通常表示将来 ,到……快结束/末尾的时候
By the end of 2007,I will go to Hainan to spend my holiday.
到2007年底的时候,我要去海南度假.