Read the sentences. Pay special attention to the word " could"

Read the sentences. Pay special attention to the word " could" in each sentence.
1. When I was three I could ride a bicycle.
2. What would you laik to do at the weekend? - We could go to the Zoo.
3 The weather was bad and we Couldn't go for a walk.
4. This year we couldn't go on a holiday all together. Let's do it next year.
5. How can I help you?- You could phone my mother. Or you could phone the doctor.
6. She was so excited she couldn't speak.
7. Where could we go on holiday next year?
Определи, в каких предлажениях could
а) является формой прошедшего медли от can и означает способность
b) обозначает возможность
Безотлагательно!!!