what are you looking for?Are you kidding me?look,kid 不都是动词吗?

what are you looking for?Are you kidding me?look,kid 不都是动词吗?为什么用are,不用do?什么时候用are,什么时候用do呢?
小弟英语语法差,现在说会说的几句话都是用语感带出来的,原理不懂,请赐教,最好详细点.