may提问的肯定回答是：yes,you can.或者,yes,please.否定回答是，no,you can't.不要用must提问，如果要表达那个意思，你可以这样说：Do you have to...can提问的肯定和否定回答同may一样。yes,you can.&no,you can't.
may和might用法的区别might后接动词的完成式，除表示对过去的推测外，还有以下用法(不用may)：
1、表示过去某事可能发生而实际上却并没发生：
A lot of men died who might have been saved．
很多人本来可以获救的却死了。
It was really very dangerous. I might have killed myself.
那真的是太危险了，我差点没命了。
2、表示委婉的批评或责备：
You might have made greater progress.
你的进步本来可更大一些的。
You might at least have answered my letter.
你至少可以回我一封信嘛。