Passage 1
Antarctica(南极洲) is the 5th largest continent(大陆). It covers approximately 5.5 million square miles; however， the actual size of the continent varies from month to month. It varies because the ice edge of the continent is always changing. The land itself is 98% covered by the Antarctic Ice Sheet， which is an average of 1.6 miles thick and holds about 90% of the fresh water on Earth.Antarctica is divided into two parts by the mountains. These mountains run between the Ross Sea and the Weddell Sea and separate east from west. East Antarctica is higher in elevation(高度). Here the ice and snow rises over 14，000 feet.Antarctica has an average elevation of about 7，500 feet. The highest point， standing at 16，050 feet， is the peak of Vinson Massif in the Ellsworth Mountain range. In contrast， the lowest point currently known is the Bentley Subglacial Trench(海沟). It is 8，200 feet below sea level. However， the trench is covered by more than 9，840 feet of ice and snow.While it may seem like there would be no bodies of water in Antarctica， it is actually home to more than 70 lakes. All of these lakes are covered by thousands of feet of ice. Lake Vostok is the largest of the lakes. It was discovered in 1996， beneath Russia’s Vostok Station.Antarctica currently receives groups of scientists who study the special environment there. The only other people who visit Antarctica arrive on some special ships. Since the 1960s， an ever increasing number of people have decided that the ideal vacation includes a tour of the Southern Ocean， with landing at some Antarctica islands extending from the continent.Antarctica has no permanent residents and， unlike all other continents， it has no native population. In fact， no one is known to have set eyes on Antarctica until 1820.