她答应父母外出时会安分守己。 He promised his mom he'd be as good as gold during the week-long summer camp. 他向妈妈保证，在为期一周的夏令营里会非常听话。 【闲话习语】 该习语起源可追溯至 17 世纪，早期用于形容物品品质如黄金般优良，19 世纪后逐渐转向形容人。