There was a woman in Detroit, who had two sons. She was worried about them, especially the younger one, Ben, 1 he was not doing well in school. Boys in his class made joked about him because he seemed so 2 . The mother 3 that she herself would have to get her sons to do better in school. She told them to go to the Detroit Public Library to read a 4 a week and do a report about it for her. One day, in Ben’s 5 , the teacher held up a rock and asked if anyone knew it. Ben put up his hand and the teacher let him 6 . Why did Ben raise his hand? They wondered. He 7 said anything, what could he possibly want to say? Well, Ben not only 8 the rock; he said a lot about it. He named other rocks in its group and even knew 9 the teacher had found it. The teacher and the students were 10 . Ben had learned all this from doing one of his book 11 . Ben later went to the 12 of his class. When he finished high school, he went to Yale University and at last became one of the best doctors in the United States. After Ben grew up, he 13 something about his mother that he did not know as a 14 .She, herself, had never learned how to 15 . 1. A. because B. so C. but D. though