赞题库-背景图

单项选择题

Which of the following environmental problems is the article talking about

A．Acid rain.
B．Ozone depletion.
C．Deforestation.
D．The greenhouse effect.

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单项选择题How much of American GNP comes from sectors that are affected by climate change

A．3%.
B．10%.
C．87%.
D．13%.

单项选择题Which of the following statements is TRUE

A．Living mechanisms are always more efficient than their artificial imitations.
B．Bats rely on their sonar system as well as eyesight to eat insects.
C．The sonar system of bats has had 50 million years to be refined.
D．People have discovered the bats' sonar system thousands of years ago.