A. Some primary and secondary school teachers have reservations about teaching at school, and their spare time has passed? Tutor? Make up lessons for children to earn money.

B. On Teachers' Day, more and more students give gifts to teachers. The relationship between teachers and students used to be described as the purest, noblest and most selfless, but now it is becoming more and more utilitarian and commercialized.

C. The number of teachers has greatly increased, which leads to management difficulties.

D. In the modern educational environment of pursuing equality and freedom, the authority of teachers has also been challenged in teaching and management.

Correct answer: ABD