he worked hard ,thus he succeeded

题目

he worked hard ,thus he succeeded
我想问为什么he 和worked 中间不加一些 比如was 或者had 什么时候加呢

答案

work hard,是表示努力工作（学习）的固定搭配词组.
was 或者 had ,表示过去时间的时候可以加入,例如 he had been working hard,thus he succeeded.
或者,he was working hard,and he succeeded.