Do you know?为啥用do?
Do除了第三人称单数主语的助动词;
一般疑问句结构:助动词+主语+谓语动词……?这里的一般现在时的一般疑问句助动词主语是you,就用do:
更多例句:
Do you understand?
Does she understand?
Do they get up early?