Exercises with Could and Couldn't

When I was young, I ___________ play the guitar: it was too difficult for me!

COULD and COULDN'T refers to ability or inability in the past.

Her grandmother was bilingual: she_________ speak both English and Spanish.

COULD and COULDN'T are the past tense forms of CAN and CAN'T

Yesterday, Peter __________ do that exercise alone. So, he called me for help.

We use COULDN'T to mean that we weren't able to do something in the present.

Mary's grandfather _______ play chess and he was the best!