More and more, the operations of our businesses, governments, and financial institutions are controlled by information that exists only inside computer memories. Anyone clever enough to modify this information for his own purposes can reap substantial rewards. Even worse, a number of people who have done this and been caught at it have managed to get away without punishment .
　　It' s easy for computer crimes to go undetected if no one checks up on what the computer is doing. But even if the crime is detected, the criminal may walk away not only unpunished but with a glowing recommendation from his former employers.
　　Of course, we have no statistics on crimes that go undetected. But it' s disturbing to note how many of the crimes we do know about were detected by accident, not by systematic inspections or other security procedures. The computer criminals who have been caught may be the victims of uncommonly bad luck.
　　For example, a certain keypunch operator complained of having to stay overtime to punch extra cards. Investigation revealed that the extra cards she was being asked to punch were for dishonest transactions. In another case, dissatisfied employees of the thief tipped off the company that was being robbed .
　　Unlike other lawbreakers, who must leave the country, commit suicide, or go to jail, computer criminals sometimes escape punishment, demanding not only that they not .be charged but that they be given good recommendations and perhaps other benefits. All too often, their demands have been met.
　　Why? Because company executives are afraid of the bad publicity that would result if the public found out that their computer had been misused. They hesitate at the thought of a criminal boasting in open of how he juggled the most confidential records right under the noses of the company' s executives, accountants, and security staff. And so another computer criminal departs with just the recommendations he needs to continue his crimes elsewhere.

　　21 . It can be concluded from the passage that _______.
　　A) it is still impossible to detect computer crimes today
　　B) computer crimes are the most serious problem in the operation of financial institutions
　　C) computer criminals can escape punishment because they can't be detected
　　D) people commit computer crimes at the request of their company
 
　　22. It is implied in the third paragraph that _______.
　　A) many more computer crimes go undetected than are discovered
　　B) the rapid increase of computer crimes is a troublesome problem
　　C) most computer criminals are smart enough to cover up their crimes
　　D) most computer criminals who are caught blame their bed luck
 
　　23 . Which of the following is mentioned in the passage?
　　A) A strict law against computer crimes must be enforced.
　　B) Companies need to impose restrictions on confidential information.
　　C) Companies will guard against computer crimes to protect their reputation.
　　D) Companies usually hesitate to uncover computer crimes.

　　24 . What may happen to computer criminals once they are caught?
　　A) With a bad reputation they can hardly find another job.
　　B) They will be denied access to confidential records.
　　C) They may walk away and easily find another job.
　　D) They must leave the country or go to jail.

　　25 . The passage mainly about _______ .
　　A) why computer crimes are difficult to detect by systematic inspections
　　B) why computer criminals are often able to escape punishment
　　C) how computer criminals manage to get good recommendation from their former employers
　　D) why computer crimes can' t be eliminated

　　答案：21. B 22. A 23. D 24. C 25. B