The document discusses two uses of the present tense: 1. To express repeated or usual actions like habits, hobbies, daily/scheduled events, or things often forgotten or not done. Examples given are playing tennis, a train's schedule, always forgetting a purse. 2. To indicate beliefs about facts, both past and present, and assumptions about the future, even if incorrect. Generalizations about people and things are also expressed this way. Examples include cats liking milk, the composition of windows, and the size of New York City.