单项选择题

The concentration of carbon dioxide is caused by ______.

A．the heat accumulated in the atmosphere
B．the burning of coal
C．the wide use of renewable energy
D．the destruction of the tropical rain forest
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单项选择题
After reading the passage, we may conclude ______.
A．the author is worried about the greenhouse effect
B．the author asks all of us to reduce the use of coal
C．the greenhouse effect is welcome as it is a mixed blessing
D．the greenhouse effect has affected our life now
单项选择题
Which of the following is Not true of the greenhouse effect
A．It will make chilly places better for agriculture.
B．Desert regions may receive more precipitation.
C．There would be less land on earth.
D．Some warm places would be cool.
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