These are periods of time when the people who want to become electricians and plumbers work for other electricians and plumbers who teach them all the things, or many of the things, they need to know.

这些时期是那些想成为电工和水管工的人为其他电工和水管工工作的时期， 这些电工和水管工会教给他们所有的东西， 或者许多他们需要知道的东西。