When I was at university，I studied very hard．But a lot of my friends did very little work．Some did just enough to pass exams．Others didn’t do quite enough．Fred Baines was one of them．He spent more time drinking in the Students’ Union than working in the library．
Once at the end of the term，we had to take an important test in chemistry．The test had a hundred questions. In my room the night before the test，Fred was watching TV．Fred usually worried a lot the night before a test．But on that night he looked perfectly calm．Then he told me of his plan．“It’s very simple．There are a hundred questions and I have to get fifty correct to pass the test．I’ll take a coin into the examination room．I haven’t studied a chemistry book for months，so I’ll just toss the coin．That way，I’m sure I’ll get half the questions right．”
The next day, Fred came happily into the exam room. As he sat tossing a coin for half an hour he marked down his answers. Then he left，half an hour before the rest of us．
The next day，he saw the chemistry professor in the corridor．“Oh，good，”he said，“Have you got the result of the test?”The professor looked at him and smiled, “Ah，it’s you，Baines．Just a minute.” Then he reached into his pocket and took out a coin. He threw it into the air, caught it in his hand and looked at it．
“I’m terribly sorry，Baines,” he said，“You failed!”
21.This story mainly wants to tell us ________．
A．chemistry is really hard to learn
B．there were too many questions for students to prepare for
C．good exam results needs hard study
D．tossing a coin can not always decide the result
22. Fred Baines was one of those who ________．
A．did just enough to pass the exam
B．did not work hard enough for their studies
C．had too much other work for the Students’ Union
D．were quite good at passing exams
23.Fred came happily into the exam room because ________．
A．he had got ready for the exam
B．he knew the answers already
C．the other students would be behind him
D．he had his way to finish the exam
24.The professor tossed the coin to tell Baines that ________.
A. he was satisfied with his way for the exam
B. he wanted to make friends with him
C. his way for the exam would never work
D. the exam result depended on the coin