spend time for maths 还是in mathsthough i spend much time _____math ,istill got "c" _____ ita\for for b\on for c\in in d\for on

spend time for maths 还是in mathsthough i spend much time _____math ,istill got "c" _____ ita\for for b\on for c\in in d\for on
spend time for maths 还是in maths
though i spend much time _____math ,istill got "c" _____ it
a\for for b\on for c\in in d\for on

spend time for maths 还是in mathsthough i spend much time _____math ,istill got "c" _____ ita\for for b\on for c\in in d\for on
spend 有两种表达：1.spend sth on sth 2 spend sth in doing sth 这里 in可以省略

应该是in

非常简单，表示花时间的用in，表示花钱的用on，这里很明显是表示花时间学数学，答案不言而喻啦，以后也不用为这种小问题烦恼啦。