Which exam do you think you will fail? Just send a message to the teacher after the exam. It's best not to call, especially when the teacher is in the office, because there are other teachers, even if the teacher wants to help, he doesn't want to be considered selfish by other teachers. In addition, you and this teacher had better not misunderstand before, or the teacher should at least know you. Otherwise, the teacher will not be willing to help you.

In fact, you should have a good relationship with the teacher at ordinary times, so that even if you don't do well in the exam, it goes without saying that the teacher won't let you fail.