释义
n.
a runner or competitor who sets the pace at the beginning of a race or competition, sometimes in order to help another runner break a record
（在赛跑或竞赛开始阶段）定速度的人；领跑者。
a person viewed as taking the lead or setting standards of achievement for others
带头人；标兵。
an artificial device for stimulating the heart muscle and regulating its contractions
（心脏）起搏器。
the part of the heart muscle (the sino-atrial node) which normally performs this role
起搏点，起步点。
the part of an organ or of the body which controls any other rhythmic physiological activity
（控制人体生理活动节奏的）节律器。