问by a car和by car的区别

by a car释义：被车例句：He died after being knocked down by a car.他被一辆汽车撞倒后死了。

Tragedy struck the family when their son was hit by a car and killed.这个家庭惨遭不幸，他们的儿子被汽车撞死了。by car释义：乘汽车例句：It's too far to walk—I'll take you by car.步行路太远，我开车送你去。