题目

阅读下面短文，掌握大意，然后从1-20各题所给的四个选项（A、B、C和D）中，选出最佳答案。 A young student was one day taking a walk with a professor, who was commonly 1the students' friend. As they went2, they saw lying in the path a pair of old 3, which they supposed to belong to a poor man who was employed in a 4 close by. The student turned to the professor, saying, “Let's play the man a5 ,We will hide his shoes, and6ourselves behind those bushes, and wait to see his7when he cannot find them.”“My young friend,” answered the professor, “we should n一个氘核（）与一个氚核（）发生聚变，产生一个中子和一个新核，并出现质量亏损，则聚变过程中 A. 吸收能量，生成的新核为 B. 吸收能量，生成的新核为 C. 放出能量，生成的新核为 D. 放出能量，生成的新核为