[误] My brother is a dance mania.

[正] My brother has a mania for dancing.

注：表示对某事的着迷或狂热，英文说 mania，但这个名词不能作主语补足语，只能用作动词 have 的宾语。其他例如 He has a perfect mania for rare books.(他有狂搜珍本书的癖好。)