题目内容：

An apprenticeship is a form of on-the-job training that combines workplace experience and classroom learning. It can last anywhere from one to six years, but four years is typical for most. An apprentice spends the majority of the time in a workplace environment learning the practical skills of a career from a journeyman--someone who has done the job for many years. The rest of the apprentice's time is spent in a classroom environment learning the theoretical skills the career requires. Being an apprentice is a full-time undertaking.

     One of the advantages of apprenticeship is that it does not cost apprentices anything. The companies that hire them pay for school. What's more, it offers apprentices an "earn while you learn" opportunity. They usually start out at half the pay of a journeyman, and the pay increases gradually as they move further along in the job and studies. Near the end of the apprenticeship, their wages are usually 90 percent of what a journeyman would receive. Apprenticeship also pays off for employers. It can offer employers a pool of well-trained workers to draw from.

     Despite the advantages, apprentices are usually required to work during the day and attend classes at night, which leaves little time for anything else. Sometimes, they might be laid off(下岗) if business for the employers is slow.

     Once they have completed the apprenticeship and become journeymen, they receive a nationally recognized and portable certification and their pay also increases again. Some journeymen continue employment with the companies they apprenticed with; others go onto different companies or become self-employed contractors.