I once listened to it with the big class, and the effect was ≈0.

The teacher talks like a baby, asking everyone from time to time if they understand. Only a few people understood, but everyone said they understood and skipped.

For the intern teacher, I can only talk about most people's problems. Sometimes I don't understand, and I dare not ask or forget to ask after class.

Undergraduate tutors are recommended. Tutoring is aimed at you. Anyway, it is charged by the hour. If you don't understand, it doesn't matter if he repeats it. If you don't understand, you can ask as many questions as possible. You're not afraid of losing face anyway.

It is also not recommended that you consult a teacher, which will make you feel uncomfortable, depressed and afraid of making mistakes.