当后面是形容词时用be ,be还有"是"的意思,表示动作在正在进行是用be
当后面是动词时,用do来提问.
例如：I am happy.(happy是形容词,和am 一起构成谓语,该句是主谓结构)
She is his mother.(她是他母亲)
He is doing his homework .(动作进行中)
当动词做谓语时提问用do
Do you finish your work?你完成你的工作了吗?(这里"finishi "是动词,故用do)
Are you good at swimming?你擅长游泳吗?(没有动词做谓语)
Do you love you mother?(这里的"love"是动词)
你多去看看书,看我说得对不?