Molly knew she could not afford to make a single slip.

【slip】莫莉知道自己一个小错误都不能犯。

Each lapse is like the letting fall of a ball of string which one is carefully winding up; a single slip undoes more than a great many turns will wind again.

每一次失误就像一团正在小心收紧的线团掉落； 一次失误所造成的损失远大于多次转弯会再次缠绕。