大学英语：The terms we would normally use

12． The terms we would normally use to describe a scientific phenomenon are inadequate here. P1
　　  13. Astronomers and scientists think that a black hole is a region of space into which matter has fallen and from which nothing can escape. P1
　　  14. Some stars explode when their density increases to a particular point. P2
　　  15. This process of shrinking may be so intense that a black hole results. P2
　　  16. It is only recently that astronomers have begun specific research into black holes. P3
　　  17. Very advanced technology could one day make use of the energy of black holes for mankind. P5
　　  18. He has exerted all his strength to attain his goal.
　　  19. He has been exerting a lot of pressure on me to change my mind.
　　  20. The collapse of the government left the country in confusion.
　　  21. The research group launched out into a series of new experiments.