1. explain the use of the present simple in the following sentences: rivers flow to the sea. 2. the student buys a lot of books at the beginning of each semester. 3. music makes me forget all my problems. 4. mr. hill lectures in philosophy at the university. 5. not shout. we can hear you clearly. 6. i see you understand. 7. the teacher asks us a lot of questions in the classroom every day. 8. there are four seasons in a year. each season lasts three months and brings changes in weather. 9. this house belongs to mr. black. 10. if paul calls us, we will invite him to dinner 11. when spring came, they would go to venice. 12. we were told you were looking for a job. 13. i forgot where she lives. 14. every weekend she gets in the car, goes to the country and works in the garden. 15. the next bus leaves at exactly 5 o'clock. 16. the ship sails every tuesday.