This view has some truth in the era of slow social development, but in today's rapidly developing society, if teachers want to give students a glass of water, it will become an ever-changing stream. A cup of stagnant water that has not been updated for a long time will become stagnant water, and a teacher's knowledge should be constantly updated with the development of the times, otherwise his knowledge will become obsolete and useless, so our teacher should update his knowledge in time.