填空题

Man is a land animal, but he is also closely tied to the sea. (26) history the sea has served the needs of man. The sea has provided man with food and a (27) way to travel to many parts of the world. Today, experts (28) that nearly two-thirds of the world’s population lives within eighty kilometers of the seacoast.
In the modem technological world the sea offers many resources to help mankind (29) . Resources on land are beginning to grow less. The sea, however, still offers hope to supply many of man’s needs.
The riches of the sea yet to be developed by man’s technology are (30) . Oil and gas (31) has existed for nearly thirty years. Valuable amounts of (32) such as iron, nickel and copper exist on the ocean floor, ready to be mined.
Fish farming promises to be a good way to produce large (33) of food. (34) .
Besides oil and gas, the sea may offer new sources of energy. (35) . Ocean currents and waves offer possible use as a source of hydroelectric power.
Technology is enabling man to explore even deeper under the sea. (36) . The development of strong, new materials has made this possible.