Is he good at diving?
No, he isn't.
What is he good at?
He's good at catching.
What is she good at?
She's good at reading poetry.
What is he good at?
He is good at diving.
What is he good at?
He's good at playing computer games but he isn't good at doing puzzles.
What are they good at?
They're good at telling jokes.
Is he good at catching?
Yes, he is.
What is she good at?
She's good at acting but she isn't good at reading poetry.