1 He couldn't go(go) to school last week because he was ill
2 He eats in restaurant all the time because he couldn't cook(cook)
3 I couldn't give(give) you a lift in my car because it isn't working at the moment
4 I didn't have a good seat in the theatre, so I couldn't see( see) the stage very well
5 Jane doesn't need calculator. She can do( do) very difficult sums in her head
6 She's very good at music. She can sing(sing) this song well
7 I couldn't find(find) my tennis racquet. Have you seen it
8 He spoke very quickly and I couldn't understand(understand) anything he said
9 We couldn't go(go) on the trip because we couldn't afford(afford) it. It was too expensive
10 I couldn't do(do) any more work because I was very tired, so I stopped