引理

lemma (math.)

to draw (e.g. a bow) / to pull / to stretch sth / to extend / to lengthen / to involve or implicate in / to attract / to lead / to guide / to leave / to provide evidence or justification for / old unit of distance equal to 10 丈[zhang4], one-thirtieth of a km or 33.33 meters

texture / grain (of wood) / inner essence / intrinsic order / reason / logic / truth / science / natural science (esp. physics) / to manage / to pay attention to / to run (affairs) / to handle / to put in order / to tidy up