v.充当（某角色的）候补演员
n.候补演员
When the star became sick,his understudy stepped into his part. 当这位电影明星生病时，由他的候补演员担任他的角色。
She got the part and I was her understudy. 她得到了这个角色，我只能作为替补的临时演员。
