Text I – questions 1 through 5

1 The range of uses for the laser is striking, going far

beyond the original ideas of the scientists who developed the

first models.

4 The wide variety of lasers is also striking. At one end of

the scale there are lasers made from tiny semiconductor chips

similar to those used in electronic circuits, no larger than grains

7 of salt. At the other end, building-size laser weapons are being

tested by the military.

The tasks that lasers perform are usually difficult or

10 impossible with any other tool. Lasers are relatively expensive

tools and are often brought in to do a job only because they can

deliver the required type and amount of energy to the desired

13 spot. Charles H. Townes, one of the inventors of the laser and

a Nobel Prize winner, said recently that he believes the laser “is

going to touch on a very great number of areas. The laser will

16 do almost anything. But it costs. That is the only limitation.”

A typical surgical laser, for example, costs from $ 30,000

to $ 50,000 and up, or about a thousand times more than a good

19 conventional scalpel. And to be honest, for many operations a

scalpel may be better than a laser. But if you have a detached

retina, a condition that could lead to blindness, you may be

22 happy that these expensive scalpels exist.

A laser can do what a knife can’t: weld the retina back to

the eyeball. No incision is required for this delicate surgery,

25 which can be performed right in the doctor’s office. The laser

beam shines through the lens of the patient’s eye and is focused

on the retina, producing a small lesion that helps hold it to the

28 eyeball. Exotic as this sounds, a similar laser treatment has

become a standard way of curing blindness caused by diabetes.

_{Brenda Wegman and Miki P. Knezevicp. A reading skills book.}

_{Third Edition. The Mcgraw-Hill Companies, Inc. (with adaptations).}

From text I, it can be gathered that

blindness can be caused by a detached retina.