这两个情态动词均含有“能，可能，可以”之意。
can 和 may 常被错用，应注意3点:
1.can 表示体力或智力方面的能力。may没有这种功能。
- Can you drive?
你会开车吗？ - She can speak four languages.
她会讲4门语言。 - Can you read that sign from this distance?
你从这么远的距离能看清楚那标牌上的东西吗？ - The doctors are doing all that they can, but she's still not breathing properly.
医生们在竭尽所能，可是她仍然不能正常呼吸。
2.can 和may 都可表示请求允许做某事，前者较口语化，最常用；may用于正式文体，多含尊敬之意。
- If you see Brett, can you tell him I'm in town next weekend?
如果你见到布雷特，能告诉他我下周末在伦敦吗？ - Can you make a little less noise, please? I'm trying to work.
请你别发出那么大声音好吗？我正在工作。
- A reader may borrow up to six books at any one time.
读者一次最多可借阅6本书。 - "May I help myself to some more food?" "Yes, of course."
“我能再取些吃的吗？”“好的，当然可以。” - Hi, my name's Tiffany. How may I help you?
“你好，我叫蒂法尼，能帮你做些什么吗？”
3.can 和 may 都可能表示可能性，前者表理论上的可能性，而后者表示现实的可能性。在这种用法中，can一般不能用来表将来的可能性，多用在否定和疑问句中表现在的可能性，而may既可表现在又可表将来的可能性。
- You can get stamps from the local newsagents.
你可以在当地的报刊销售店买到邮票。 - You can get very nasty skin diseases from bathing in dirty water.
在脏水里洗澡会得严重的皮肤病。 - Smoking can cause cancer.
吸烟可能会导致癌症。 - Noise can be quite a problem when you're living in a flat.
住公寓噪音会很成问题。 - He can be really annoying at times (= he is sometimes very annoying).
有时候他很烦人。
- There may be other problems that we don't know about.
可能有我们不知道的其他问题。 - I may see you tomorrow before I leave.
明天我走前也许还能见到你。 - The cause of the accident may never be discovered.
事故的原因也许永远无法查清。 - The explosion may have been caused by a faulty electrical connection.
爆炸可能是由电路连接错误引起的。 - We'd better not interfere - she may not like it.
我们最好别干涉——她可能会不高兴。 - There may be some evidence to suggest she's guilty, but it's hardly conclusive.
也许有迹象显示她有罪，但不怎么令人信服。
