問題詳情

Laser eye surgery is very popular. Each year, more than one million Americans have this type of surgery performed. In the United Kingdom, more than eight thousand people per week undergo the procedure. This is what happens: a very thin layer of the cornea is cut and lifted up. (Its thickness is approximately that of a human hair.) The cornea is never completely severed from the rest of the eye; it remains attached to the remaining cornea, just like a hinge. The exposed tissue is then lasered. When the lasering is completed - and it usually takes no longer than 30 to 90 seconds per eye - the cornea is placed back in its original position. The surgeon then replaces the flap in exactly the same position. No stitching is needed. Nothing is ever inserted directly into the eye. All these advanced techniques result in a very short, post-surgical recuperation period. The patient will experience minimal discomfort during and after the surgery, and, most often, the patient’s eyesight will be dramatically improved. No wonder this procedure is so popular!
81.What is a ‘cornea，? It is
(A)a pair of classes.
(B)a piece of cake.
(C) a softener
(D)a piece of transparent tissue over the front of the eyeball.

參考答案

答案：D
難度：簡單0.75
統計：A(0),B(0),C(4),D(12),E(0)

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