Здравствуй!
3.1 2) are building; 3) is swimming; 4) are standing; 5) is coming; 6) am cooking; 7) is having.
3.2. В самом описании задания не сказано про отрицательные предложения,но это исправимо легко.
3.2 3) I am sitting on a chair; 4) I am not eating;
5) It is raining; 6) I am learning English; 7) I am not listening to the radio; 8) The sun is shining; 9) I am wearing shoes; 10) I am smoking a cigarette; 11) I am not reading a newspaper.

3.3 2) In A the man is doing physical excercises. In B he is standing on the chair.
3) In A it is pouring. (перевод:" сейчас льёт как из ведра",на самом деле можно употребить много синонимов здесь).In B the sun is shining.
4) In A the boy is writing a letter. In B the girl is reading a letter (e.g. textbook,card,newspaper,так как на картинке не явно отображен объект.)
5) In A the person is running. In B the person is riding a bicycle.
6) In A the woman is driving a car. In B the woman is not driving a car.
Успехов!