Ex.5
1. When I was two I could walk
2. My friends couldn't go to the disco
3. Could you speak English last year?
4. I could ride a bike two years ago
5. Could you play chess ten years ago?
Ex.6
1. You should play a game
2. You shouldn't open the window
3. You should buy a drink
4. You should have a sandwich
5. You shouldn't play computer games at night