18．As they migrate（迁移），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 employ 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 thousands of feet above ground． Only recently i have scientists developed technologies that can detect such little creatures at such great heights．
To their surpri se，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 wIntenng 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．Many migrating birds do the same thing．
The study also found，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 when farmers decide when to spray their crops．
71．Whatl S the main idea of the text？C
A．Insects migrate with the seasons．
B．Wind helps insects greatly in migrating．
C．Windsurfing insects have real direction．
D．Scientists have trouble in observing insects．
72．Scientists originally thought thatC．
A．insects always waited for their favourable winds
B．insects chose the winds they wanted to ride
C．insects were j ust blown about by the wind
D．insects posi tioned themselves in the winds
73．It is not easy to stuay the migrating behavior of the insects becauseD
A．the little creatures can fly very fast
B．they have no regular migrating courses
C．the wind's direction is hard to f．oresee
D．their flight is long and high above ground
74．We can learn from the text thatA
A．insects fly in the way birds do
B•insects travel more easily in autumn
C．insects never position themselves when flying low
D．insects rest a lot when the wind pushes them along
75．According to the passage，the findings canB．
A．increase insects in number B．instruct farmers when to spray
C．prevent climate warming D．help protect insects．
分析 本文是一篇科教类阅读，主要讲述了帆板类昆虫也有真正的方向．
解答 71-75．CCDAB
71题答案：C考查主旨大意，本文主要讲了实际上帆板类昆虫其实也是有方向的，而不是像人们以为的任由风摆布；故本题答案为C选项．
72题答案：C考查细节推理，根据原文第二段的最后一句Scientists have long thought that insects were simply at the mercy of the wind．科学家长期以来一直以为昆虫只是任由风摆布．可知本题答案为C选项．
73题答案：D考查细节推理，根据原文的 because many long distant trips happen thousands thousands of feet above ground．因为很多长距离的旅行发生在距离地面数以千计英尺的高空．可知本题答案为D选项．
74题答案：A考查细节推理，根据文章首段的This new finding suggests that insects may employ some of the same methods that birds use for traveling long distances．该项新的发现表明昆虫可能运用了鸟类远距离飞行的某些方法．可知本题答案为A选项．
75题答案：B考查细节推理，根据文章最后一段的Knowing how and when these pests move could help when farmers decide when to spray their crops．知道这些昆虫是如何及何时移动（迁徙）能够帮助农民决定何时浇灌庄稼．故本题答案为B选项．
点评 本文是一篇科教类阅读，题目涉及多道细节理解题，做题时结合原文和题目有针对 性找出相关语句进行仔细分析，结合选项选出正确答案．推理判断也是要在抓住关键句子的基础上合理的分析才能得出正确的答案．
