A: Professor Smith seems to be angry.
B: His lesson was so boring that many of us dozed off in class.
A: No wonder.
exp. To fall asleep, typically unexpectedly or for just a short period of time. （不知不觉地打起盹来）
e.g. Whew, I must have dozed off there for a few minutes. What did I miss?
e.g. I dozed off in front of the TV for a few minutes.
e.g. Do not doze off in the middle of the meeting .
e.g. Before I had time to doze off again, I was disturbed by a rattling of plates and dishes in the servant's hall.
e.g. This teacher is so kind that we all like him.
e.g. He ran so quickly that we all couldn’t catch up with him.
e.g. He has so many books that I can’t count them.
Children who talk too much in class get under the teacher's skin.
e.g. I will amend my ways and stop talking in class.
e.g. He slept badly at night and couldn't concentrate in class at daytime.
e.g. She was kept in for an hour for talking in class.