5. Work in pairs. Explain the difference between sentences a and b in each pair.
(Làm việc theo cặp. Giải thích sự khác nhau giữa các câu a và b trong mỗi cặp.)
1. a. I'm doing my homework after school.
b. I do my homework after school.
2. a. Joe is learning to drive.
b. Many teenagers learn to drive when they are seventeen.
3. a. Mark plays the guitar.
b. Mark is playing the guitar.