单项选择题

According to the passage, which of the following statements concerning Edison's electric light bulb is true

A．It replaced gas as a light source.
B．It increased the need for electric power.
C．It was safer than any other methods of lighting.
D．It could work only with electricity generated from coal.

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单项选择题

The author suggests in the passage that _________.

A．there will certainly not be enough raw materials for the world economy in the year 2008.
B．world petrol supplies will have been exhausted by 1985
C．we need to use natural resources carefully and divide them up equally
D．to show down the economic growth in developed countries might be a possible solution to the problem

单项选择题

If we take immediate action, the population in the southern parts _________.

A．would not stop growing.
B．would level off in fifty years.
C．could stabilize in about seventy-five years.
D．could soon be brought under control.