[单项选择]The floors of the ocean have many riches that can be used by man. Oil and chemicals and minerals (矿物) already are taken from the sea. By using nuclear energy, ocean water can be turned into fresh water by taking the salt out. In the near future, it is possible for human beings to produce food from farms under the sea. Food grown in the sea could help to meet the needs of population all over the world which is increasing fast. Thousands of people go hungry every day. About ten to fifteen percent of the world’s people do not have enough food. Some scientists believe that someday the sea will be used to make electric power. This would help to meet the need for more power for the world’s industries. The decreasing supply of coal, oil and gas shows that the need to find new kinds of power is urgent.
Human beings have already made use of ______ .
A. nuclear energy in the lab under the sea
B. salt water resource as fresh water
C. minerals, chemicals and oil taken from the sea
D. farms under the sea

[单项选择]The floors of the ocean have many riches that can be used by man. Oil and chemicals and minerals (矿物) already are taken from the sea. By using nuclear energy, ocean water can be turned into fresh water by taking the salt out. In the near future, it is possible for human beings to produce food from farms under the sea. Food grown in the sea could help to meet the needs of population all over the world which is increasing fast. Thousands of people go hungry every day. About ten to fifteen percent of the world’s people do not have enough food. Some scientists believe that someday the sea will be used to make electric power. This would help to meet the need for more power for the world’s industries. The decreasing supply of coal, oil and gas shows that the need to find new kinds of power is urgent.
We can learn from the passage that ______ .
A. there are now many farms under the sea producing food
B. more than one tenth of the world’s people are suffering from hunger
C. the supply of oil, gas and coal are increasing rapidly throughout the world
D. it is unnecessary for man to make full use of the riches of the sea

[单项选择]Many theories about the origin of the ocean have been proposed by scientists. The most widely accepted one is that the earth at some time in its very early history became hot enough to melt the materials from which it was formed. While in this molten state, lighter rock-forming materials (造岩材料) floated on the surface of the heavier ones. Then, between four and a half four billion (十亿) years ago, the molten earth cooled sufficiently to form a crust of rock that was many miles thick.
Surrounding the earth was an unbroken canopy of clouds miles thick and made up mostly of water vapor. Rain falling toward the still-hot earth was heated to steam and rose to the clouds again. After many millions of years, as the earth continued to cool, its surface temperature fell below the boiling point of water. Rainwater could now remain on the earth, covering its whole surface except for the higher places on earth that had been formed from the lighter rock materials.
In 1970, scientists had pi
A. the origin of the earth
B. the origin of the ocean
C. the history of the earth
D. the forming of the earth’s crust