In America, before the motor vehicle, transportation depended entirely on the urban horse, which dropped, without restraint, 25 to 50 pounds of manure on the streets every day together with a gallon of urine.
美国的交通完全依赖马匹。 由于没有限制， 这些马匹每天在街上要排放25磅至50磅的粪便， 还有1加仑的尿液。