yu jie with his grandparents lives in the country.为什么用lives?

yu jie with his grandparents lives in the country.为什么用lives?
yu jie with his grandparents lives in the country.为什么用lives?

yu jie with his grandparents lives in the country.为什么用lives?
如果把这句顺序变一下你就能理解了,YU JIE LIVES IN THE COUNTRY WITH HIS GRANDPARENTS.主语只是YU JIE,所以用LIVES.

这不有with吗！ 有with就遵循就远原则，也就是跟离动词最远的那个名词一致

with其实是一种伴随状态，主语是with前面的，以后你遇到except,也是这样子。
既然主语是第三人称，肯定要用三单形式拉~