He lived with his grandma,and his parents were working in another city

问题描述:

He lived with his grandma,and his parents were working in another city
这两件事都是表示存在的状态,为什么前面用过去时,后面用进行时?

他跟奶奶一起住,当时他的父母在另外一个城市工作.
从我的翻译里可以看出来吗?前面用过去时说的是过去的一个事情,后面用 were working 是与当时的动作同时进行,为了强调是同一时间进行的动作,所以用过去进行时.