Can, could and may at Grandma's house

Can, could and may are small helping words. They go before another verb, and that verb stays plain: can cook, could climb, may go. We never add -s, -ed or -ing to the verb after them.

We use can to show ability (what someone is able to do now): Grandma can grind pepper on her grinding stone. We use could for ability in the past: When I was five, I could not reach the window.

We use may to ask for or give permission: May I sit on the bench, Grandma? Yes, you may.

May and could also show possibility, something that might happen or might be true: The goats may be behind the hut. It could rain tonight.