A Until quite recently the opportunities for criminal activity on the Internet have been low. However, the volume of business done on the Internet is growing rapidly, as people order books and other products and make money transactions(交易). All this is creating temptation for hackers. Hackers are often young people who are addicted to computer. They use them to move quietly on the Internet, looking for ways to break into computer system run by banks, telephone companies and even government departments. They look for examples of credit cards and try to steal the numbers. Recently in America, hackers have been caught testing the security system at the Pentagon(五角大楼), headquarters of American Defence Department. But still the hackers persist for a dare "because it's there" although with what success nobody really knows. Hackers rarely admit to a successful break-in. The first indication of a security breach may be when a customer discovers a fraudulent(诈骗的) money transaction on a credit card account. It's harder to check on somebody misusing an online connection unless there is a massive download of information which would alter the consumer. The two ways to defeat hackers are: 1) to have an up-to-date virus scanner which can recognize the invaders and delete it; 2) to change one's password constantly. 1. What are hackers trying to steal? A: Money transactions. B: Credit cards. C: Security systems. D: Credit card numbers. 2. One of the effective ways against hackers is _______. A: always changing computers B: always changing passwords C: always changing systems D: always changing virus scanners 3. We can infer from the passage that _______. A: it was safer to make money transactions before B: it is safer to order books and other products than make money transactions C: the security system at the Pentagon is hackers' only headache D: it is for the bank to know whether their customers misuse an online connection 4. In the passage hackers are compared to _______. A: thieves B: robbers C: consumers D: shoplifters