be better at 和 be better in的用法及区别

be better at (是 be good at 的比较级)：擅长于……； 在……方面做得好.= do better in 好像没be better in 这种用法.He is good at maths ,but he is better at English .也数学学得好,但他英语更好.加油!不明白...请问 Tom is better ________ English than me while I do better ________ Math than him. A. in---inB. in---at C. at---in D. in---in 选哪个？C固定用法 ：be good / better at do well / better in