At the same time, the Net is increasingly populated with spiders, worms, agents and other types of automated beasts designed to penetrate the sites and seek out and classify information. All these make wonderful tools for antisocial people who want to invade weak sites and cause damage.

　　But let’s look on the bright side. Given the lack of locks, the Internet is surely the world’s biggest (almost) crime-free society. Maybe that is because hackers are fundamentally honest. Or that there currently isn’t much to steal. Or because vandalism (惡意破壞) isn’t much fun unless you have a peculiar dislike for someone.

　　Whatever the reason, let’s enjoy it while we can. But expect it all to change, and security to become the number one issue, when the most influential inhabitants of the Net are selling services they want to be paid for.

　　21. By saying “…owners of well over half of all World Wide Web sites have set up home without fitting locks to their doors” (Line 3-4, Para.2), the author means that ______.

　　A) those happy times appear still to be with us

　　B) there simply wasn’t any crime to worry about

　　C) many sites are not well-protected

　　D) hackers try out tricks on an Internet site without actually breaking in

　　22. SATAN, a program designed by Dan Farmer, can be used ______.

　　A) to investigate the security of Internet sites

　　B) to improve the security of the Internet system

　　C) to prevent hackers from breaking into websites

　　D) to download useful programs and information

　　23. Farmer’s program has been criticized by the public because ______.

　　A) it causes damage to Net browsers

　　B) it can break into Internet sites

　　C) it can be used to cause disorder on all sites

　　D) it can be used by people with evil intent

　　24. The author’s attitude toward SATAN is ______.

　　A) enthusiastic

　　B) critical

　　C) positive

　　D) indifferent

　　25. The author suggests in the last paragraph that ______.

　　A) we should make full use of the Internet before security measures are strengthened

　　B) we should alert the most influential businessmen to the importance of security

　　C) influential businessmen should give priority to the improvement of Net security

　　D) net inhabitants should not let security measures affect their joy of surfing the Internet