the是特指某一个的意思，人名，本身已经含有特指某个人的意思，所以人名前面不用加“the”
例句:
Tom entered the room after Jerry. 汤姆跟着杰瑞进入了房间。
At that time she was sitting behind Mary. 那时她坐在玛丽的身后。
behind用作介词的用法例句:
Who is the girl standing behind Richard?站在理查德后面的那个姑娘是谁
The train was 10 minutes behind time.火车晚到了十分钟。
Britain is behind Japan in developing modern technologies.在发展现代技术方面英国落后于日本
