Exercise 1: Choose the word (a, b, c, or d) that best fits each of the blank spaces.

Computers are very (1)____, but they also can (2) _____ problems. One kind of problem is with the computer’s memory. It is not perfect, so (3) ____ computers lose (4)______information. (5)_____ problem is with the machinery. Computers are machines, and (6)_____can break down. When computers break down, they (7)______erase information, like chalk on a blackboard. Or they may stop doing anything at all. And there is another different kind of problem with computers. Some doctors say they may be bad for your (8)_____. They say you should computers all day.

(1)...................

• A. 
  useful
• B. 
  careful
• C. 
  helpful
• D. 
  a&c