Of course, other variables, both known (dedicated bagger) and unknown (payment type, coupons, cigarettes) affect on the speed of the line, but this is a good rule of thumb to use as a baseline.

• 当然，有些变化的因素，诸如知道的因素（专业装袋工）和不知道的因素（结账方式，优惠券，香烟）会影响速度，但是这是一个不错的基础准则。