黑暗骑士，蝙蝠真英雄

李全忠

蝙蝠是飞行高手，且是唯一能振翅飞翔的哺乳动物。夜间，蝙蝠靠声波探路和捕食。当声波遇到物体时，声波会像回声一样返回，由此蝙蝠就能辨别出这个物体是移动的还是静止的，以及离它有多远。

More than 1，400 bat species live around the world， except in Antarctica and a few remote islands. What makes these flying mammals so successful？ “It is clear that bats do have supernatural powers，” says an ecologist called Rodrigo Medellín.

Supernatural power 1： Echolocation （回聲定位）

Many bats do not rely on vision as their primary sense， but use echolocation to navigate and find food in complete darkness.

Echolocation is a way of noticing the environment by bouncing high⁃frequency sounds off objects and listening for their echoes. From these echoes， bats can calculate the distance， size， and shape of objects， such as a tasty mosquito. Some bats can detect an object as small as the width of a human hair.

Supernatural power 2： Speedy flight

Bats are the only mammals that use their muscles to fly， which makes their flight techniques unique in the animal kingdom.

The flexible wings， packed with blood vessels， nerves and tendons （腱）， are supported by special muscles that make bats efficient and quick fliers. Unlike bird or insect wings， bat wings can fold during flight in various ways， similar to the way that a human hand can close into different shapes.

Supernatural power 3： Longevity

As a general rule in biology， smaller animals have shorter life spans than larger ones. But bats are rule breakers： Theyre the longest⁃lived mammals relative to their body size. The oldest bat ever recorded was a tiny Brandts bat in Russia， which weighed less than a quarter of an ounce， yet lived at least 41 years.

Supernatural power 4： Resistance to viruses

In addition to living longer， bats remain healthy throughout their lives， with very low incidences of cancer. In any case， wild bats carrying coronaviruses do not threaten humans if left undisturbed. Research into their unique immune systems may actually give insight into how people can live with viruses and not get sick.

Supernatural power 5： Keeping the environment healthy

Beyond their own abilities， bats also improve many other parts of their ecosystems.

Three out of every four bat species eat insects. Many are pests that cause damage to important agricultural crops， such as cotton. Whats more， many bat species boost （使增长） plant health and diversity： At least 549 plant species are either pollinated （授粉） or spread by bats. Therefore， bats provide crucial services to ensure our food， clothes， and drinks. Its high time that we should appreciate them.

1. Which of the following helps bats greatly find directions and food？

A. The sense of smell.

B. The sense of sight.

C. The sense of hearing.

D. The sense of touch.

2. Whats special about bats flight skills？

A. Theyre the only animals flying at night.

B. They can use muscles to fly as mammals.

C. Theyre the fastest fliers in the animal kingdom.

D. They can hardly fly with their wings folded.

3. Whats the advantage of studying the immune systems of bats？

A. It may help bats live longer.

B. It may keep bats safe during the pandemic.

C. It may help people deal with viruses better.

D. It may keep the diversity of plant species.

4. In what way do bats improve ecosystems？

A. By controlling their weight.

B. By fighting against viruses.

C. By providing food for insects.

D. By eating insects and keeping plants healthy and diverse.

Sentence for writing

Its high time that we should appreciate them. 我們是时候感谢它们了。

【信息提取】Its high time that...意为“该是（做）……的时候了”，that 后面的从句谓语动词要用过去式或用“should+动词原形”，should不可省略。

【句式仿写】孩子们是时候睡觉了。

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