The one who makes the heads of the pins must be certain of the co operation of the one who makes the points if he does not want to run the risk of producing pin heads in vain.

• 从事于针头操作的人，如果要使他有把握他的劳动力不致于白费，则对于从事于针尖操作的另一工人的协作，必须毫无疑虑。