Basics. Modal verbs to convey necessity, possibility, permission, or ability.

Choose the correct sentence to express that Lucy was able to play the piano when she was a child.

Answers:
- [ ] Lucy might play the piano when she was a child.
- [ ] Lucy must play the piano when she was a child.
- [X] Lucy could play the piano when she was a child.
- [ ] Lucy can play the piano when she was a child.
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"Could" is used to express past ability or knowledge of how to do something. The correct sentence is "Lucy could play the piano when she was a child."
