s/he

剑桥词典

used in writing instead of "she or he" to refer to a person whose sex is not known
（在书面语中代替 she or he，表示某人性别未知）他或她
If any employee needs to take time off, s/he should contact the Personnel Department. 任何雇员需要休假，应与人事部联系。
也见 they 返回 s/he