正确答案: D

To explain a basic tie between birds and human beings.

题目：22.请阅读Passage 2,完成第1～5小题。 　　Passage 2 　　Birds are a critical part of our ecological system.But more than ever,birds are threatened byhuman pollution and climate change. 　　We need the birds to eat insects,move seeds and pollen around,transfer nutrients from sea toland,clean up after the mass death of the annual Pacific salmon runs,or when a wild animal falls anywhere in a field or forest. 　　How could we enjoy spring without the birds fiitting busily in our garden or dropping by to check out the fiowers in our urban window box? Can you “contemplate” America without the soaring bald eagle,or even those scavengers like the pigeons and gulls that clean up discarded food scrapson our city streets and waterfronts? How diminished our lives would be without “them”? 　　Scavenging eagles and condors need hunters to behave responsibly and bury,or remove,theremains of any shot deer peppered with fragments of lead bullets.loons,ducks and other water birds will be poISOned by lead bullets and lead fishing sinkers if we allow such objects to drop intheir feeding space. 　　All sea and shore birds,even the puffins and guillemots of the otherwise pristine Aleutians,need us to make sure that no other heavy metals,like mercury and cadmium,are dumped in rivers and make their way across the oceans. 　　Birds like the terns,knots and shearwaters that migrate between the far north and deep,deep,south of our planet need people everywhere to cease and desist from filling in their wetland fuelstops and rest stations,and from constructing golfing resorts and factories in their feeding and breeding grounds. 　　Seabirds are among the most endangered vertebrate species on the planet,with the International Union for Conservation of Nature classifying 97 species as globally threatened,and 17 in thehighest category of critically threatened.Of greatest concern are the pelicans of the southern oceans and the spectacular,but slow-breeding albatross. 　　Plastic bags must be eliminated from natural environments so sea and shore birds don'tmistakenly carry such debris back to feed their chicks,with invariably lethal consequences.The albatross,cormorants and herons need us to stop over-fishing and compromising their normal foodsupply. 　　The pelicans,pengujns and all the birds that inhabit,or visit,our coastlines need us to ensurethat we do not dump oil into gulfs and bays,or release so much carbon dioxide into the atmospherethat the oceans turn acidic and we lose the mussels and oysters,the mass of calcareous plankton thatfeeds so many creatures,and the coral reefs that nurture enormous numbers of edible species. 　　Think about it:We share this small green planet.As they fly,feed and nest,the birds monitorthe health of the natural world for us,provided that we,in turn,make the effort to access that keyinformation.The birds and humans are both large,complex and ultimately vulnerable organisms that inhabitthe top ofthe food chain.At the end of the day,their fate will be our fate.

解析：主旨题。文章第一段指出鸟类是生态系统的关键一环，但是鸟类正面临前所未有的人为污染和气候变化的威胁；第二、三段介绍鸟类对生态环境、城市以及人类生活的重要性；第四至九段介绍人类应该如何保护鸟类；最后两段再次点明鸟类和人类是相互依存的关系，最终，它们的命运就是我们的命运。由此可见作者写此文的目的是为了解释鸟类和人类的基本关系，故本题选D。

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学习资料的答案和解析：

[单选题]He looks like a Scottish,but his accent may give him______.

away

解析：本题考查动词短语辨析。句意为"他看起来像一个苏格兰人，但是他的口音可能暴露了他"。give off"发出，放出（气味、热、光等）"，give out"分发，公布"，give in"屈服，让步"，give away"暴露，泄露"。根据句意可知本题选D。

[单选题]teachers can apply all ofthe following methods to teaching stress except________.

relying on detailed explanations

解析：本题考查语音教学。教师可以采用拍手或挥动手臂的方式帮助学生练习重音，还可以在重音处提高声音，或在黑板上用粉笔将重音画出来。四个选项中只有D项不合适，