People are often uncertain about whether there is any difference between can and may when these verbs are used to ask for or grant permission.
当动词can和may用来表达请求或授予许可时，人们常常不确定这两个词是否存在不同。
看看下面两个例子是否有不同：
Can I ask you a few questions?
May I ask you a few questions?
Can常用于与能力或技能相关的疑问句中，如：
Can she swim?
她会游泳吗？
Can you speak Italian?
你能说意大利语吗?
May可以表示推测,意为“也许,可能”.如：
She may be at home. Let’s go to see him.
她可能在家，我们去看看她吧。
用作请求时：
The difference between the two verbs is that one is more polite than the other. In informal contexts it’s perfectly acceptable to use can; in formal situations it would be better to use may.
这两个词语的区别就是一个词语（may）比另一个（can）更为礼貌。在非正式的场合使用can是完全可以被接受的，在正式场合则使用may更为合适。
因此，上面两个句子都是正确的，只是使用may会更正式和礼貌一些。
小测验：选择正确的词语
1.____ I use your eraser?
can may
2.____you play the piano?
can may
答案：Can/May(更正式)；Can
