1. lt was very late so I couldn't write an e – mail to my pen–pal.
2. They could throw the rubbish at the school yesterday.
3. We could go to the park yesterday.
4. The robot could do the cleaning.
5. My father could repair the computer two days ago.
6. My friend couldn't call me last week.
7. I couldn't go to England by plane because I was afraid of ‘height'.
8. I couldn't buy that mobile phone because it was too expensive.
9. I was very ill week but I could go to the school.
10. We could use the ‘Microsoft Word' on PC last Wednesday.
Answers:
a) 9 b) 3 c) 8 d) 2 e) 7
f) 6 g) 4 h) 10 i) 1 j) 5