资料：When we see well，we do not think about our eyes very often. It is only when we cannot see perfect

资料：When we see well，we do not think about our eyes very often. It is only when we cannot see perfectly that we realize how important our eyes are.People who are near-sighted can only see things that are very close to their eyes，Everything else seems blurry（=unclear）.Many people who do a lot of work，such as writing，reading and sewing become near-sighted.People who are far-sighted suffer from just the opposite problem. They can see things that are far away，but they have difficulty in reading a book unless they hold it at arm’s length. If they want to do much reading，they must get glasses，too.Other people do not see clearly because their eyes are not exactly the right shape. They have what is called astigmatism. This，too，can be corrected by glasses. Some people’s eyes become cloudy because of cataracts. Long ago these people often became blind. Now，however，it is possible to operate on the cataracts and remove them.Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle. To prove this to yourself，look at an object out of one eye；Then look at the same object out of your other eye. You will find the object’s relation to the background and other things around it has changed. The difference between these two different eye views helps us to judge how far away an object is. People who have only one eye cannot judge distance as people with two eyes.Having two eyes instead of one is particularly useful for______.
A：looking over a wide area
B：seeing objects far away
C：judging distances
D：seeing at night
C
本题考查的是细节理解。 【关键词】Having two eyes instead of one；useful for 【主题句】第5自然段Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle.拥有两只好眼睛对于判断距离非常重要。每只眼睛从略微不同的角度看东西。 【解析】本题的问题是“两只眼睛相较一只眼睛对于______特别有用。”A选项“俯瞰广阔的区域”；B选项“远处看物体”；C选项“判断距离”；D选项“晚上看东西”。根据主题句，C选项正确。
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