Choose the correct answer. do a favor for do favor for. Choose the correct answer. do (or cause) damage do (or cause) a damage. Choose the correct answer. do a service for do service for. Choose the correct answer. do harm do a harm. Choose the correct answer. do an examination do examination. Choose the correct answer. do an exercise do exercise. Choose the correct answer. do an experiment do experiment. Choose the correct answer. play a joke on play joke on. Choose the correct answer. play a trick on play trick on. Choose the correct answer. beg pardon beg a pardon.