阅读下面这篇短文，短文后有2项测试任务：(1)第23～26题要求从所给的6个选项中为第2—5段每段选择1个正确的小标题；(2)第27～30题要求从所给的6个选项中选择4个正确选项，分别完成每个句子。
Alaska
1. In 1868 Americans welcomed Alaska into the Union as the 49th state, symbolizing a change of attitude from that held in 1867, when the peninsula was purchased from Russia. Then, most Americans had little interest in 1,500,000 square kilometers “of icebergs and polar bears”— beyond Canada’s western borders, far from the settled areas of the United States.
2. In those sections of the state which lie above the Arctic Circle, Alaska still is a land of icebergs and polar bears. Ice masses lie buried in the earth, which is permanently frozen to a depth of 90 or more meters. From early May until early August, the midnight sun never sets on this flat, treeless region, but the sun cannot melt the icy soil more than two-thirds of a meter down.
3. Alaska is America’s largest state, but only about 325,000 people live there. According to estimates, 800,000 hectares of its land area are fit for plowing but only about 640,000 hectares are being cultivated.
4. Arctic Alaska has been the home of Eskimos for countless centuries. It is believed that the Eskimos moved there from Mongolia or Siberia, probably crossing Bering Strait, named for Vitus Bering, the Danish sea captain who discovered Alaska on his voyage for Russia in 1741. The Eskimos are the state’s earliest known inhabitants. Russian fur traders established settlements but, by the time Alaska was sold to the United States, most of the traders had departed.
5. In 1896 gold was discovered near the Klondike River in Canada just across the Alaskan border. Thousands of Americans rushed to the region on their way to Klondike; some never returned. Alaska was never completely cut off again, although even today transportation is a major problem. There are only two motor routes from the U. S. mainland, and within the state, every town has its own airfield. Planes fly passengers, mail and freight to the most distant villages.
6. The gold that changed life so suddenly for Alaska was soon ended, and although many stories about mining camps have become part of American literature, the gold from Alaskan earth contributed less to economic progress than the fish from Alaskan waters. The fish caught in a single year range in value from $ 80 million to $ 90 million. Fur-bearing animals are plentiful in the forests and streams, and valuable fur seals inhabit the waters. After fishing, the state’s chief industry is lumber and the production of wood pulp. In recent years, Alaska’s single most important resource has become oil. The state also has large deposits of coal, copper,gold and other minerals. Paragraph 3 ______ A. Rich resources of the state