This document discusses modal verbs and how they are used to modify the meaning of other verbs. It provides examples of common modal verbs like can, could, will, shall, must, should, might, and may. It explains how modal verbs are used to show ability, likelihood, advice, permission, obligation, and habits. It provides exercises for learners to practice identifying modal verbs, making them negative, choosing the right modal verb, and matching pictures to sentences containing modal verbs.