1. As an auxiliary verb, "can" generally means "to be able" or "to be capable," and is used to express ability, possibility, or permission. For example: "I can swim."2. As a noun, "can" refers to a cylindrical metal container or more generally to any canned food. For example: "She opened a can of beans."3. As a verb, "can" means to preserve food by canning or, informally, to fire someone. For example: "He canned the soup."4. In speech, "can" can be used to make requests or grant permission, often interchangeably with "may" but with a more colloquial tone. For example: "Can/May I sit here?"5. When "can" is used to make guesses, it conveys a weaker tone than "must" (definitely). For example: "The book must be Wang's, her name is on it."6. The positive sentence structure with "can" is "Subject + can + base form of verb + other," indicating that someone is able to do something. For example: "They can play basketball."7. The negative sentence structure is "Subject + cannot (can't/cannot) + base form of verb + other," expressing that someone cannot or does not know how to do something. For example: "We can not make heavy concession to the matter."8. The general question structure is "Can + Subject + base form of verb + other," used to ask if someone can do something. For example: "Can you sing an English song for us?"9. The special question structure is "Who + can + base form of verb + other," used to ask who is capable of doing something. For example: "Who can sing in English in your class?"10. Proverbs related to "can" include: "A man can do no more than he can," "You can't judge a tree by its bark," and "Beggars can’t be choosers."