While walking the dog,you were careless and it got loose and was hit by a car.

问题描述:

While walking the dog,you were careless and it got loose and was hit by a car.
这里walking是现在分词做伴随状语吗?用现在分词做伴随状语需要什么条件吗?而且补全时为什么要用you are 而不是 you were

是由一个主语发出两个动作或同一个主语处于两种状态,或同一个主语发出一个动作时又伴随有某一种状态.伴随状语的逻辑主语一般情况下必须是全句的主语,伴随状语与谓语动词所表示的动作或状态是同时发生的.所以补全是you were.