Passage One
　　Questions 56 to 60 are based on the following passage．

　　Thousands of years ago man used handy rocks for his surgical operations．Later he used sharp bone or horn, metal knives and more recently, rubber and plastic and that was where we stuck，in surgical instrument terms，for many years．In the l960s a new tool was developed，one which was，first of all，to be of great practical use to the armed forces and industry, but which was also，in time，to revolutionize the art and science of surgery,
　　The tool is the laser and it is being used by more and more surgeons all over the world，for a very large number of different complaints．The word“laser”means：light amplification by stimulated emission of radiation．As we all know,light is hot，any source of light—from the sun itself down to a humble match burning—will give warmth．But light is usually spread out over a wide area．The Light in a laser beam，however，is concentrated．This means that a light with no more power than that produced by an ordinary electric light bulb becomes intensely strong as it is concentrated to a pinpoint-sized beam.
　　Experiments with these pinpoint beams showed researchers that different energy sources produce beams that have a particular effect on certain living cells．It is now possible for eye surgeons to operate on the back of human eye without harming the front of the eye，simply by passing a laser beam right though the eye-ball．No knives，no stitches，no unwanted damage—a true surgical wonder. Operations which once left patients exhausted and in need of long period of recovery time now leave them feeling relaxed and comfortable。So much more difficult operations can now be tried.
　　The rapid development of laser techniques in the past ten years has made it clear that the future is likely to be very exciting．Perhaps some cancers will be treated with laser in a way that makes surgery not only safer but also more effective．Altogether, tomorrow may see more and more information coming to light on the diseases which can be treated medically．

56．Which of the following is NOT a tool used for surgical operations before the 1960s?
A)Bone．
B)Metal knives．
C) Scissors．
D)Rubber and plastic．

57．The appearance of the laser in the l960s results in_____.
A)a complete revolution in the，science of surgical techniques
B) an end to pain brought by all diseases
C) medical help accessible to more common people
D) complete changes in man’s approach to surgery

58．What is the reason mentioned in the passage that the laser beam is so strong?
A) It sends out light to cover a wide area． 
B)It has many sources of light.
C) It is a highly concentrated beam of light．
D)The source of its heat comes from the sun.

59．The author cites the example of eye surgeons to illustrate that
A) pinpoint beams have an extensive energy source
B) pinpoint beams with different sources have different effects
C) pinpoint beams have effects on living cells
D)pinpoint beams enable surgeons to do the most different operation

60．The rapid development of laser techniques means that
A) in another ten years we shall be able to cure cancer
B) we shall be capable of treating all the diseases
C) patients do not have to suffer any pain
D) surgery is likely to improve considerably

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