填空题

At the bottom of the world lies a (36) continent still wrapped in the Ice Age and, until recent times, (37) to man. It is a great land miss with mountain ranges whose (38) and elevation (高度) are still uncertain. Much of the continent is a complete (39) on our maps. Man has explored, on foot, less than one percent of its area. Antarctica differs (40) from the Arctic regions. The Arctic is an ocean, covered with (41) pack ice and bordered by the land masses of Europe, Asia, and North America. The Antarctic is a continent almost as large as Europe and Australia (42) , centred roughly on the South Pole and (43) by the most unobstructed (无障碍的) water areas of the world-the Atlantic, Pacific, and Indian Oceans. The continental ice sheet is more than two miles high in its centre; thus, the air over the Antarctic is far more refrigerated than it is over the Arctic regions. (44) .And it renders unlivable those regions whose counterparts at the opposite end of the globe are inhabited. (45) . This area includes most of Alaska, Siberia, and Scandinavia-a region rich in forest and mining industries (46) .