Use could whenever possible in the following sentences. Negative forms may be necessary. When could is not possible, use another appropriate form. Again, you may need to choose a negative form. Finally, decide in each case what kind of modality is being conveyed: permission, ability or mere possibility.

1. He’d already had two sandwiches and a chocolate bar. He ___ eat anything else.

2. She ___ date boys starting at the age of 16.

3. Her results were very bad that term, but she ___ go to the dance all the same.

4. Like modern-day elephants, mammoths ___ grow six sets of adult teeth in a lifetime.

5. I ___ eat anything when I was a child. I wasn’t picky at all.

6. He ___ ride a bike when he was six.

7. We ___ smoke on the school premises. If we did, we got in trouble.

8. Although I was exhausted, I ___ do my usual 10-mile run last night.

9. When we walked into the house last night, we ___ smell something burning.

10. The horse-drawn carts of the mid-1800s ___ reach speeds of up to 20 miles per hour.

11. He ___ speak Russian quite well when he was young.

12. In the end, I ___ explain to the gendarme that my passport had been stolen.

13. Sarah didn’t pick up when I phoned her, but I ___ contact her later via e-mail.

14. Before Sarah was promoted, you ___ contact her at the office more easily.

15. Several lucky concert-goers ___ go backstage last night to meet the band.