单项选择题
A．someone who breaks into and uses someone else's computer B．someone who breaks commercials C．someone who fixes someone else's computer D．someone who does not know about computers
A．made by the hackers and put on computers B．not found by the experts C．prepackaged and found on many computers D．hard to find
A．computers are hard to reach B．everyone has their computers locked C．computers are not very secure D．companies ask them to do it