do a person a favor
= do a favor for a person答應某人的請求,幫某人的忙,給予某人恩惠 Will you do me a favor? 你願意幫我忙嗎?
do a person good
對 <人 (的身體) > 有益 Smoking won't do you any good. 吸煙對你的身體無益 It will do you more harm than good. 它對你的害處多于益處; 它對你有害無益 Much good may it do you !. (反語)但願它對你大有用處(它對你沒什麼用處)
