The document discusses the use of modal verbs to express future possibility and draw conclusions. It explains that "may", "might", and "could" are used to express future possibility, while "must", "have to", and "have got to" indicate nearly certain conclusions. When conclusions are less certain, "may", "might", and "could" are used, and negative conclusions can be expressed by "can't", "couldn't", "must not", or "may not/might not". Questions about possibility often use future tense or phrases like "Do you think", while answers often contain modal verbs.