单项选择题

This passage mainly discusses ______.

A．the functions of carbon dioxide and water
B．the role of water in a growing plant
C．the process of simple sugar formation
D．the synthesis of water with carbon dioxide

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单项选择题

The essential function of photosynthesis in terms of plant needs is ______.

A．to derive energy from light
B．to preserve water
C．to combine carbon dioxide with water
D．to form sugars

单项选择题

The second paragraph uses facts to develop the idea that ______.

A．a plant needs more water than is found in its composition
B．a plant efficiently utilizes most of the water it absorbs
C．the stronger the wind, the more water vapor the plant loses.
D．carbon dioxide is the essential substance needed for plant development