存在于生物体内的重要物质，是生命的基础

current, present, now, nowadays

当着对方的面, 面对面

immediately, at once, at that moment, at the moment

受别人委托代表他处理事务

don, guide of a great cause, hierophant, teacher, tutor, imam, supervisor, leader in a cause, preceptor, professor, preceptorship, adviser, teacher in charge of class, mentor, counselor