3.1.

2. are building

3. is swimming

4. are standing

5. is coming

6. am cooking

7. is having

3.2.

3. I am sitting on a chair.

4. I'm not eating.

5. It's not raining.

6. I am learning English.

7. I'm not listening to the radio.

8. The sun isn't shining.

9. I'm not wearing shoes.

10. I'm not smoking a sigarette.

11. I'm not reading a newspaper.

3.3.

2. In A the man is lying beside a chair. In B he is standing on the chair.

3. In A it's raining outside. In B the sun is shining through the window.

4. In A the boy is writing a letter. In B the girl is reading a book.

5. In A the man is running. In B the man is doing cycling.

6. In A the woman is driving a car. In B the man is driving a car.