英语阅读A teacher stood in front of his history class of twenty

英语阅读
A teacher stood in front of his history class of twenty students just before handing out the final exam.His students sat quietly and waited for him to speak.
“It’s been a pleasure teaching you this term,” he said.“You’ve all worked very hard,so I have a pleasant surprise for you.Everyone who chooses not to take the final exam will get a ‘B’ for the course.”
Most of the students jumped out of their seats.They thanked the teacher happily,and walked out of the classroom.Only a few students stayed.The teacher looked at them.“This is your last chance,” he said.“Does anyone else want to leave?” All the students there stayed in their seats and took out their pencils.
The teacher smiled.“Congratulations (祝贺),” he said.“I’m glad to see you believe in yourselves.You all get A’s.”
51.This story most probably took place .
A.at the beginning of the term B.in the middle of the term
C.at the end of the term D.at the beginning of the school year
52.Most of the students got Grade ______.
A.‘A’ B.‘B’ C.‘C’ D.‘F’
53.Why did some students stay in their seats?
A.Because they wanted to take the exam.
B.Because the teacher told them to stay in their class.
C.Because they were afraid to leave.
D.Because they didn’t have anything to do.
54.The teacher gave the students who stayed in the classroom A’s because ______.
A.the teacher liked them
B.they were cleverer than the other students
C.they believed in themselves
D.they studied hard
55.The underlined word “them” in Paragraph 3 refers to “______”.
A.students staying in their seats B.students leaving the classroom
C.their seats D.all the students