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阅读理解
阅读下面文章，根据文章内容，从每小题所给的A、B、C、D四个选项中选出能回答所提问题或完成所给句子的最佳答案。
It was so dark outside the car window that is was hard to see anything．
“Can I have a carrot, Mum?” Riley asked．
“I don't have any carrots,” her mum said．“How about an apple?”
“No,” said Riley．“It has to be a carrot．”
“Why do you want a carrot?” asked her mum．
“You always say carrots help your eyes,” said Riley．“If I eat one now, it might help me see in the dark．”
Would eating a carrot really help Riley? What is special about carrots? A clue to what makes a carrot special is its color．Carrots are orange because they store beta-carotene(胡萝卜素)．Beta-carotene is a way to talk about Vitamin A(维生素A)．Your eyes need Vitamin A．It helps them work．
When light hits your eye, very small parts inside turn the light into messages．The messages go to your brain(脑),and then you know what you're looking at．Your eye can only turn light into messages when it has a special chemical(化学物质)．That's where Vitamin A comes in．Your eyes use Vitamin A to make the special chemical．Every time your eye changes light to messages, a little bit of the chemical is used up．By the end of the day, you've looked at hundreds of things．That uses up a lot of the chemical．Your eyes need to make more．
What should you eat if you don't like carrots? Don't worry．Other fruits and vegetables have Vitamin A too．The secret is in their color．Most orange or red fruits store some beta-carotene, or Vitamin A．Sweet potatoes, red peppers, mangoes(芒果)are a few that have the same orange secret．Can you think of any more?
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