As they migrate, butterflies and moths c

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As they migrate, butterflies and moths choose the winds they want to fly with, and they change their body positions if they start floating in the wrong direction. This new finding suggests that insects may use some of the same methods that birds use for traveling long distances. Scientists have long thought that insects were simply at the mercy of the wind.

Fascinating as their skills of flight are, migrating behavior has been difficult to study in insects because many long distant trips happen thousands of feet above ground. Only recently have scientists developed technologies that can detect such little creatures at such great heights.

To their surprise, though, the insects weren't passive travelers on the winds. In autumn, for example, most light winds blew from the east, but the insects somehow sought out ones that carried them south and they positioned themselves to navigate directly to their wintering homes.

Even in the spring, when most winds flowed northward, the insects didn't always go with the flow. If breezes weren't blowing in the exact direction they wanted to go, the insects changed their body positions to compensate(补偿, 弥补). Many migrating birds do the same thing.

The study also found that butterflies and moths actively flew within the air streams that pushed them along. By adding flight speeds to wind speeds, the scientists calculated that butterflies and moths can travel as fast as 100 kilometers an hour. The findings may have real-world applications. With climate warming, migrating insects are growing in number. Knowing how and when these pests move could help farmers decide when to spray their crops.

小题1:What's the main idea of the text?

A.Insects migrate with the seasons.

B.The wind helps insects greatly in migrating.

C.Windsurfing insects have real direction.

D.Scientists have trouble in observing insects.小题2:Scientists originally thought that _____.

A.insects always waited for their favorable winds

B.insects chose the winds they wanted to ride

C.insects were just blown about by the wind

D.insects positioned themselves in the winds小题3:It is not easy to study the migrating behavior of the insects because ______.

A.the little creatures can fly very fast

B.their flight is long and high above ground

C.the wind's direction is hard to forecast

D.they have no regular migrating courses小题4:According to the passage, the findings can ____

A.increase insects in number

B.instruct farmers when to spray their crops

C.prevent climate warming

D.help protect insects

考点:科教类阅读
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用蒸笼蒸馒头,是上层还是下层蒸格中的馒头先熟呢?小明仔细观察后发现:高温的水蒸气经过多层蒸格向上升,遇到冷的蒸笼盖时,大量水蒸气发生   现象,   很多热量,使   层蒸格中的馒头先熟。有经验的师傅拿刚出笼的馒头前,先将手沾点水,这样做主要是利用     ,使手不会被烫伤。

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计算机为什么采用二进制计数?

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人民警察义务,是指人民警察在行使权力,履行职责过程中必须作出或不得作出一定行为的约束。人民警察义务的特点不包括( )。

A.人民警察义务主体的特定性
B.人民警察义务具有平等性
C.人民警察义务直接决定于国家的任用行为
D.人民警察义务的紧迫性

题型:阅读理解

在贯彻传授知识与培养能力相结合原则时,要求做到()。

A.教师要努力提高自身的科研能力

B.重视基础学科和基础知识的教学

C.注意培养学生的学习兴趣

D.注意培养学生的基本能力

E.在尊重学生的基础上对学生提出严格的要求

题型:阅读理解

根据《纪律条令》规定,行政看管的时间需要延长的,累计不得超过()天。

A、8

B、9

C、15

D、30

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