A student went to college after     1    all his school examinations. There he put his name down for world geography,     2    after the first day, he did not go to     3    any more. The teacher noticed that this student was     4    absent and thought that he had changed to     5    class. He was very     6    when he saw the boy's name on the list of students     7    wanted to take the geography examination     8    the end of the year.
    The teacher had prepared a difficult examination paper, which covered     9    he had taught, and he was eager to see     10    this student answered the questions. He expected that his answer would be very     11    ; but when he examined his paper carefully, he found only one small mistake in them.     12    this surprised him very much, he went through the paper     13    , but was still not able to find     14    one mistake, so he sent     15    the student to question him about his work. When the student had     16    the room, the teacher said to him, "I know that you came to my class only once on the first day and that you have been absent from all the others. Yet I have found only one small mistake in your paper.     17    is that?"
    "Oh, I'm sorry about that mistake, sir," answered the student. "After the examination, I realized     18    I ought to have written. I would not have made that mistake     19    I had not been confused by your     20    lecture."