do you know how后面加什么

拓展：Do you know how to do it?

(用how时加宾语it)和Do you know what to do?(用what时不加宾语)因为what本身是代词,就可以直接做do的宾语,而how是副词,不能做宾语；且do做及物动词,所以后面要补充出其宾语。