[单项选择] Man is a land animal, but he is also closely tied to the sea. Throughout history the sea has served the needs of man. The sea has provided man with food and a convenient way to travel to many parts of the world. Toady, experts believe that nearly two-thirds of the world’’s population live within eighty kilometers of the seacoast. In the modern technological world the sea offers many resources to help mankind survive. Resources on land are beginning to grow less. The sea, however, still offers hope to supply many of man’’s needs in the future. The riches of the sea yet to be developed by man’’s technology are impressive. Oil and gas explorations have existed for nearly thirty years. Valuable amounts of minerals such as iron, copper and so on exist on the ocean floor. Besides oil and gas, the sea may offer new sources of energy. For example, warm temperature of the ocean can be used as the steam in a steamship. Sea may also offer a source of energy as electricity for m
A. In the next generation.
B. By the end of the 20th century.
C. In the near future.
D. By the middle of the 21st century.