下面两句话那个对the reason why i got a job was because i word hard / was that i work hard.

The reason why I got a job was that I work hard.

两句都不对，应该是这样的

The reason why I got a job was that I worked hard.

第二个靠谱，但也不准确。
The reason why i could get a job was that i work hard.
加个情态会好些。

应该是The reason why I got a job was that I work hard.因为the reason why...be动词后面不可能跟because引导的原因状语从句