When David Williams left the college, he went to Australia. When he returned to England for a visit twenty years later, he decided to go back to his old college.
David was very glad when he found out that his old college teacher was still teaching there. He went to visit the old man, and after they had an interesting talk, the teacher went out to get something. While he was away, David saw an exam paper on the desk. He looked at the date on it and saw that it was given to the students a week ago. David picked the paper up and read it. When  the teacher came back, David said to him, ”Mr. Smith, I’m sure that these are right the same questions that you asked us in our exams twenty years ago! How is that possible?”
“Yes, that’s right,” agreed the teacher. “The questions are the same, but the answers have changed.”
45. David went to______  after he left the college.
A. England       B. Australia      C. another college       D. his teacher’s office
46. David felt ______ when he found out that his college teacher was still teaching there.
A. worried      B. sorry      C. surprised       D. happy
47. The students took the same exam_____.
A. twenty years ago         B. while David’s teacher was away
C. a week ago              D. while David read the paper
48 Can you guess why the teacher still used the same exam paper twenty years later? Because______.
A.times have changed, answers have changed, too  B  different students have the same answers  
C. the students like to take the same exam       D. the teacher loved his students very much