下面的短文有10處空白，每處空白后的括號(hào)內(nèi)有一個(gè)詞，請(qǐng)根據(jù)短文內(nèi)容將其正確的形式填入文中，以恢復(fù)文章原貌。

Problems Caused by Using Computers

Long hours at the screen can cause     41    (ache) eyes,     42   (blur) vision and headaches,  experts say. In fact, eyestrain surpasses even wrist pain as the top physical  ___43__ (complain) among heavy computer users. When peering into the computer screen, the eye's focusing muscle is at constant tension. Like any muscle, it feels sore when  ____44___(overload) . And when someone spends a lot of time looking at something close, the eye muscle can get  ____45___(stick) on the near-focus setting and have difficulty relaxing, leaving the person    46    (temporary) nearsighted, a condition called accommodative spasm (痙攣) that can last seconds or hours. The letters on the screen are not as clearly  ____47___(define) as on a printed page. Take a magnifying glass to your monitor and you'll see the letters. each made up of pinpoint sources of light, have no sharp edges. But those liquid crystal display (LCD) monitors, like those found on laptop computers, are    48    (easy) on the eyes be-cause they display sharper images. And studies have shown that when people are working on a computer, their rate of  ____49___ (blink) goes down by two-thirds, which can result in dry, stinging eyes. This is especially a problem for contact-lenses    50    (wear) . 

Tension in life can increase the likelihood of getting a stomach ulcer.

• A、True
  
  

• B、False
  
  

• C、Not Given
  
  

Now doctors can successfully cure stomach ulcers.

• A、True
  
  

• B、False
  
  

• C、Not Given