Questions 1 to 5 are based on the following passage.　　Comput

Questions 1 to 5 are based on the following passage.　　Computer users fed up with hacker attacks and other security threats that exploit holes in Microsoft software are increasingly turning to alternatives such as open source Internet browsers developed by Mozilla.　　“It’s reflective of a trend that we’ve seen over the last year with more web users becoming frustrated with the Internet experience,” said Chris Hoffmann of the Mozilla Foundation, a non-profit group supported by Sun Microsystems, IBM and other companies, backing as an alternative to Microsoft.　　Much of that frustration has centered on Microsoft, which has been heavily criticized for producing software vulnerable to hand virus writers. Microsoft has responded with a series of patches designed to plug vulnerabilities in its Windows operating system, Internet Explorer web browser and other software.　　But computer owners are growing weary of continuously updating software to protect against new threats. One incident last month enabled hackers to gain access to web surfers’ computers by taking advantage of vulnerabilities in Microsoft’s browser.　　Hackers could then install remote access Trojan programs that enabled them to control a victim’s computer. The hackers could also install software to capture a victim’s keystrokes to steal data such as bank account numbers and passwords.　　Mr. Hoffmann hoped publicity stemming from Microsoft’s security woes(灾难) would translate into a market share increase for Mozilla’s software, which includes the new highly regarded Firefox Internet browser.　　But Mozilla suffered a setback last week when it was forced to issue a software patch to counter a newly discovered vulnerability affecting its Internet browsers.　　Still, Mr. Hoffmann said Microsoft’s security woes stem in part from the way its browser has been integrated into Windows for user convenience. Security experts agree that has made it easier for hackers to exploit computers running on Microsoft software.　　Others suggest Microsoft has been targeted by hackers and virus writers simply because more than 90 per cent of the world’s computers run on the software giant’s operating system.　　Questions:　　1．What is the meaning of the phrase “fed up with” (Para.1)?　　2．It can be guessed that the word “plug” (Para.3) means ________________.　　3．Why more web users have become frustrated?　　4．What happened to Mozilla’s Internet browsers last week?　　5．How would Microsoft be less vulnerable?