Ero Carrera is watching the computer screen in a lab in California as he tracks a new computer virus slowly circling the globe, targeting cell phones. Working from the US office of the Finnish computer 21 firm, Carrera knows this virus could be the start of something big and 2 2  . He’s one of a couple of hundred “virus hunters” worldwide who guard computers and cell phones from 23 . That’s the job for these unlikely action heroes of the Internet age, where quick and curious minds are more important than strong 24 . Carrera works with Tzvetan Chaliavski to form the two-man team in California. Like that of other employees in the anti-virus companies in the world, their work is at the battle front of providing 25 from the damaging of computer virus, worms and Trojans. They break down software to discover a new virus and crack its code. Then they 26 and ship out a software update to customers. Roughly 300 new samples of viruses await the pair on a(n) 27 day. Carrera has created a mathematical formula(公式), to 28 easily the software structure of viruses. With it, he is better able to compare the many variants(变种) and families of malware(恶意软件). To his 29 , Chaliavski, it doesn’t even matter why someone would create a virus. All that 30 is the hunt. 21. A. advertising         B. commercial                    C. printing                   D. security 22. A. admiring             B. exciting                   C. inviting                   D. threatening 23. A. attack                B. bombing                 C. competition                    D. struggle 24. A. heads                 B. feelings                   C. muscles                   D. spirits 25. A. access                B. contact                    C. measures                 D. protection 26. A. copy                  B. create                  C. delete                  D. download 27. A. average               B. original                   C. previous                  D. special 28. A. get off               B. make out                 C. pick up                   D. take in 29. A. assistant              B. manager                  C. partner                           D. secretary 30. A. ignores               B. matters                    C. overlooks                D. rejects