2、can and cannot (or can’t ) are the most common words used for asking for, giving or refusing permission. can和cannot（或cant）是表示请求、给予或拒绝许可的最通用词：can i borrow your calculator?我可以借用你的计算器吗。
3、may (negative may not ) is used as a polite and fairly formal way to ask for or give permission. may（否定式may not）用以表示礼貌的正式请求或给予许可：may i borrow your newspaper?把你的报纸借我看行吗。