good at something—proficient in a subject or an activity:
- Boys and girls rate themselves as being equally good at science at the primary-school level.
good on something—skilful in one’s performance on a musical instrument:
- Hayes said that Pearl was “quite good” on the violin and also proficient on the mandolin.
good with something—competent in the use of smth.:
- He was very good with horses—he worked with them so that they trusted and respected him.