When do you use can shall and will?

Answer 1

The verb "can" means to be physically able or capable of doing something. I can speak French (I am physically able to do it; I know the words, I have the skill). But it is not correct to use "can" when asking permission. Use "could," which is considered more polite-- "Could I borrow your book? Could I use your computer?"

The verb "will" refers to an action that takes place in the future. I will study Spanish next year (I am not studying it now, but plan to do so later on). In questions, it can also mean "do you intend to"-- as in, "Will you be at the meeting?" But again, for permission, use "would": "Would you help me with my homework?"

As for "shall," it is a verb that is not as commonly used in American English as it used to be. It used to be a first person singular or plural (used with "I" or "we") to refer to a (definite or planned) future action, and it was considered polite: I shall go to visit my aunt next week. We shall see them at the wedding. But these days, "shall" and "will" are often used interchangeably, with one (shall) being more formal, and the other (will) being more conversational. In England, and in former British colonies, "shall" is still seen as the more polite or more correct form for the first person ("I" or "we"), whereas "will" is more definite and much stronger: "Yes I will take this course." But in America, you rarely hear "shall" as much as you did 100 years ago.

Answer 2

• "Can" is used to express ability or permission, e.g. "I can swim" or "Can I leave early?"
• "Shall" is used to make suggestions, offers, or to ask for advice, e.g. "Shall we go for a walk?" or "What shall I do?"
• "Will" is used to talk about future actions, predictions, or promises, e.g. "It will rain tomorrow" or "I will help you with your homework."