The United Nations declared 2011 to 2012 the Year of the Bat. The campaign was launched as a way to strengthen efforts for protecting the world's only flying mammal. These creatures can be found in many parts of the world. Bats live in cities, deserts, grasslands and forests. There are over 1,200 bat species.The smallest bat in the world is from Southeast Asia. This kind of bat measures about 30 millimeters in length. The world's largest bat, the Giant Golden-Crowned Flying Fox, has a wingspan of 1.5 meters. Most bats eat insects, but many feed on fruit or nectar from flowers.Many people think bats are blind, but this is not true. Bats can fly in total darkness, because ________.A. their eye sight is extremely sharpB. they can fly without using their sightC. they don't have eye sight in daytimeD. they are very familiar with their environment
The United Nations declared 2011 to 2012 the Year of the Bat. The campaign was launched as a way to strengthen efforts for protecting the world's only flying mammal. These creatures can be found in many parts of the world. Bats live in cities, deserts, grasslands and forests. There are over 1,200 bat species. The smallest bat in the world is from Southeast Asia. This kind of bat measures about 30 millimeters in length. The world's largest bat, the Giant Golden-Crowned Flying Fox, has a wingspan of 1.5 meters. Most bats eat insects, but many feed on fruit or nectar from flowers. Many people think bats are blind, but this is not true. Bats can fly in total darkness, because ________. A. their eye sight is extremely sharp B. they can fly without using their sight C. they don't have eye sight in daytime D. they are very familiar with their environment
题目解答
答案
我们来逐步分析这道题：
题目大意：
题目讲述的是蝙蝠的一些基本信息，比如它们的分布、种类、体型、食性等。最后一句话是一个填空题，问的是：“很多人认为蝙蝠是盲的，但其实不是。蝙蝠可以在完全黑暗中飞行，因为______。”
选项如下：
A. 它们的视力极其敏锐
B. 它们可以不靠视力飞行
C. 它们在白天没有视力
D. 它们非常熟悉自己的环境
解题思路：
题目考查的是对蝙蝠飞行机制的理解，特别是它们在黑暗中飞行的能力。
我们逐个分析选项：
-
A. 它们的视力极其敏锐
这个选项的问题在于，虽然蝙蝠的视力可能不错，但它们在完全黑暗中飞行的能力并不是因为视力好。因为“完全黑暗”意味着没有光线，视力再好也没用。所以这个选项不符合逻辑。 -
B. 它们可以不靠视力飞行
这是正确的。蝙蝠在黑暗中飞行主要依靠的是回声定位（echolocation）。它们发出超声波，然后通过接收回声来判断周围物体的位置和距离，从而导航飞行。这与视力无关，因此这个选项是正确的。 -
C. 它们在白天没有视力
这个选项是错误的。蝙蝠在白天是有视力的，虽然它们的视力可能不如人类，但它们并不是完全看不见。而且，这与题干中“在完全黑暗中飞行”的能力无关。 -
D. 它们非常熟悉自己的环境
这个选项虽然听起来合理，但并不是蝙蝠在黑暗中飞行的根本原因。熟悉环境可以帮助它们飞行，但蝙蝠可以在陌生的黑暗环境中飞行，所以这个不是主要原因。
正确答案：
$\boxed{B}$
总结：
蝙蝠之所以能在完全黑暗中飞行，是因为它们使用回声定位，而不是依靠视力，因此正确答案是 B. 它们可以不靠视力飞行。
解析
考查要点：本题考查学生对蝙蝠飞行机制的理解，特别是它们在完全黑暗中飞行的能力。关键在于理解蝙蝠如何感知环境，而非依赖视觉。
解题核心：回声定位是蝙蝠在黑暗中导航的核心机制。需排除与视觉相关的干扰选项，抓住“不依赖视力”的本质。
选项分析：
-
A. 他们的视力极其敏锐
错误。完全黑暗中无光，视力无法发挥作用，即使视力好也无济于事。 -
B. 他们可以不靠视力飞行
正确。蝙蝠通过回声定位（发出超声波并接收回声）感知环境，完全不需要视力。 -
C. 他们在白天没有视力
错误。蝙蝠在白天有视力，但此选项与“黑暗中飞行”无关。 -
D. 他们非常熟悉自己的环境
错误。熟悉环境可能辅助飞行，但蝙蝠能在陌生环境中飞行，说明这不是根本原因。