A laser is a device that produces a very special kind of light. Lasers are expensive tools. Charles Townes, who is one of the inventors of the laser and won a Nobel prize, said, “Laser is going to touch on a very great number of areas. The laser will do almost everything; but it is expensive. That is the only limitation.” For example, a typical surgical laser costs from 30,000 $ to 50,000 $. It is about a thousand times more than a good conventional scalpel. To be honest, for many operations a scalpel may be better than a laser. But if you have a certain kind of cancer, a laser can do what a scalpel cannot. A laser will kill the diseased cells and leave the healthy ones unharmed. The beam can cut with a precision that no scalpel can do. 22. A laser produces…………. A. a special light B. tools C. a device D. invention 23. What is the limitation of the laser? A. It produces a very special king of light. B. It cannot be used in operations. C. It is expensive. D. It cannot be used in cancer treatment. 24. Which sentence is not true? A. The laser will do almost everything. B. Charles Townes won a Nobel prize C. Charles Townes is one of the inventors of the laser. D. The laser cannot be used in cancer treatment. 25. For many operations……………….. A. a laser is cheaper than a scalpel. B. a laser does harm to cell. C. a scalpel may be better than a laser. D. a scalpel may be more precise than a laser. 26. In caner treatment……………… A. a scalpel is the only tool that can be used. B. a laser will destroy healthy cells C. a laser will kill the diseased cells and leave the healthy ones unharmed. D. a scalpel can do nothing.