split hairs
过于计较
A:My mother likes to split hairs.
A:我妈妈太过于计较了。
B:What do you mean by that?
B:你这话是什么意思?
A:She's keen to buy something which is much cheaper.
A:她喜欢买更便宜的东西。
B:Mothers are like that.
B:母亲都是这样。