supererogatory
adj. 额外的,超出职务的
1. more than is needed, desired, or required;
It was supererogatory for her to gloat ( Mary McCarthy )
她也在一旁幸灾乐祸地看得出神,真是多余 ( 玛丽麦卡锡 )
It was supererogatory of her to gloat.
她没必要幸灾乐祸.
needless