1. The document discusses modal verbs in English like can, could, may, might, must, should, will, shall, would, ought to, have to, and have got to. It explains how they are used to express ability, duty, necessity, wanting, and permission.
2. It provides examples of how modal verbs behave differently than normal verbs by always being followed by a base verb form and not taking -s in the third person simple present. It also notes they use "not" for negation rather than "do not".
3. The document outlines substitutes for modal verbs that cannot be used in all tenses, like using "will" instead of "can" or "could