11. At that time, we did not fully grasp the significance of what had happened. 　　A. give 　　B. attach 　　C. lose 　　 D. understand 　　12. Anderson left the table, remarking that he had some work to do. 　　A. doubting 　　B. saying 　　C. thinking 　　D. knowing 　　13. He asserted that nuclear power was a safe and non-polluting energy source. 　　A. maintained 　　B. recommended 　　C. considered 　　D. acknowledged 　　14. The study also notes a steady decline in the number of college students taking science courses. 　　A. relative 　　B. general 　　C. continuous 　　D. sharp 　　15. She always finds fault with everything. 　　A. criticizes 　　B. simplifies 　　C. evaluates 　　D. examines