But if all of them had worked separately and independently without division of labor, they certainly could not have made twenty pins in a day and not even one.

【参考答案】

但是，如果所有人不分工，只是各自做各自的，一天之内绝不可能生产出12磅重的钉子，甚至连1磅重的钉子也生产不出来。