听力原文： Web filtering is just one method or restricting access to the Internet. Here are some countries that have tried to control or track their residents' online activities, according to Reporters Without Borders. Saudi Arabia—The government filters all traffic through a central server and recently issued regulations banning access to sites considered subversive, contrary to the State or its system or damaging to the dignity of the heads of state. Burma—Except for some government officials and businessmen, few people in this military-controlled country have access to the Internet. A colonel was jailed after visiting an opposition political site. China—Internet service providers must install filters that block the Web sites of many Western media outlets, Taiwan and Hong Kong newspapers, human rights groups and the Falun Gong, the banned illegal movement. The government has set up a special Internet police unit. Britain—Last year the Regulation of Investigatory Powers Act extended police phone-tapping privileges to the Internet. If asked, companies and individuals would have to help law enforcement officials decode lawfully obtained data. Russia—The government has instituted an Internet surveillance system that requires service providers and telephone operators to reroute data traffic to local law enforcement headquarters, allowing authorities to monitor phone calls or e-mail. Australia—The government does not filter the Internet, but the Broadcasting Services Act defines forbidden online content, including specific representations of sexual acts and information on crime, violence and the use of certain narcotics. Questions: 11. According to the reporters, how do the mentioned countries control or track their residents' online activities ? 12.Which countries track net activities, according to the report? 13.Who was jailed after visiting an opposition political site? 14.What has the government of China set up in order to supervise the illegal Web activities? 15.Which of the forbidden online content is not mentioned? (31)