Nature has devised many ways to protect creatures’ eyes. The most common protection is the eyelid—a fold of skin that closes ove

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问题     Nature has devised many ways to protect creatures’ eyes. The most common protection is the eyelid—a fold of skin that closes over the eye, protecting it from damage. Eyelashes are useful for keeping out dust and other irritants, and tears wash away any particles that get through the other defenses.
    Some creatures, including most birds, have three eyelids. The upper and lower lids act like human lids and keep out twigs, dirt and sand. The third eyelid, however, is a semitransparent tissue that crosses over the eye from the inside corner to the outside corner. Because of this protective membrane, birds seldom have to blink. They close their eyes only when they go to sleep. In ducks, this third eyelid self as an underwater diving mask that helps the ducks find food.
    Most fish and snakes have no eyelids at all. Instead, a hard glassy covering protects their eyes. In fish, water constantly sweeps away dirt from the covering. And a snake’s eyesight is usually so bad that a little dirt obscuring its vision does not disturb it greatly.
    Eyelashes defend the eye by shading it from glare. They also act like miniature brushes to remove dust. Camels have lashes that are four inches long to protect their eyes from windblown sand in the desert.
A good title for this passage would be______.

选项 A、Look Out
B、Birds’ Eyes
C、Eyes in the Night
D、Protecting the Eye

答案D

解析 选项B是错的。文章不光讨论了鸟,也讨论了鱼、蛇等;文章讨论的焦点不是眼睛而是眼皮。选项D是正确的。文章讨论了保护眼睛的是什么。
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