四、完形填空。
主题群:自然生态
子主题:动物习性
语篇类型:说明文
词数:316
难度:★★☆
Wake up early enough and, depending on where you live, you'll likely hear the pleasant singing of birds. This is 1 in many places, but why do they sing in the early morning?
According to the Woodland Trust, this early singing can start as early as 4 a.m. and last for several 2 . Birds do it to attract mates(配偶) and 3 other birds to avoid their area. One theory is that they choose early morning hours to send these messages because low visibility(能见度) makes it hard to do other activities, like 4 food. By keeping their activity level low, they sing 5 .
Another 6 is that birds sing in the morning to show they are strong. It isn't easy for birds to live in the 7 . By singing cheerfully, they show they have made it 8 through the night and that they would be a good partner.
Like a good recording studio, the early morning hours also 9 birds' singing to travel clearly thanks to the cooler, drier air. This makes it easier for other birds to tell who is singing 10 .
There used to be a common belief that birds sang so much in the mornings because the sounds could 11 greater distances (距离) because of less air movement. But researchers at the University of Western Ontario found 12 was not true. They played sparrow(麻雀) 13 in the morning and at noon. The songs didn't travel farther, 14 they were more consistent(连续的).
Birds only have so much energy to sing, so it makes sense for them to do it when they have the best 15 of being heard. For a bird, an early morning is like having the perfect environment for its performance.
1. A. strange
B. special
C. simple
D. common
2. A. days
B. hours
C. weeks
D. months
3. A. warn
B. memorize
C. teach
D. help
4. A. waiting for
B. searching for
C. thinking of
D. looking at
5. A. together
B. again
C. instead
D. wisely
6. A. problem
B. theory
C. reason
D. report
7. A. building
B. sky
C. wild
D. house
8. A. easily
B. safely
C. happily
D. quickly
9. A. get
B. spread
C. encourage
D. allow
10. A. hardly
B. out
C. widely
D. nearby
11. A. move
B. travel
C. spread
D. carry
12. A. this
B. who
C. what
D. which
13. A. recordings
B. sounds
C. calls
D. voices
14. A. but
B. and
C. so
D. or
15. A. time
B. place
C. chance
D. way

1. D 根据“Wake up early enough and ... you'll likely hear the pleasant singing of birds.”可知，清晨听见鸟鸣是“常见的”。
2. B 根据下文 they choose early morning hours 可知，鸟鸣持续几个“小时”。
3. A 根据 other birds to avoid their area 可知，此处指“警告”其他鸟类。
4. B 根据 food 及鸟类的生存活动可知，此处指“寻找”食物。
5. C 因为觅食困难，所以它们“转而”去唱歌，instead 符合语境。
6. B 根据前文“One theory is that ...”可知，此处指另一个“理论”。
7. C 根据“It isn't easy for birds to live in the ...”及鸟类的自然生存环境可知，wild 符合语境。
8. B 根据 through the night 及生存挑战可知，此处指“安全”度过。
9. D 根据“birds' singing to travel clearly thanks to the cooler, drier air”可知，空气使鸟鸣能够清晰传播。
10. D 根据 tell who is singing 及清晰传播的目的可知，此处指分辨“附近的”鸣叫者。
11. B 根据 greater distances 及声音的传播特性可知，travel 符合语境。
12. A 根据前文“a common belief that ...”可知，此处指代“这个观点”。
13. A 根据“played sparrow ... in the morning and at noon”可知，研究人员播放的是提前录制的“录音”。
14. A 根据 didn't travel farther 和 were more consistent 可知，前后分句之间是转折关系，用 but。
15. C 根据“when they have the best ... of being heard”及能量有限的语境可知，此处指被听到的“机会”。

【分析】
这是一篇围绕鸟类晨鸣原因展开的科普说明文，解题时首先要通读全文，明确文章核心主题，理清行文逻辑：文章先后介绍了关于鸟类晨鸣的不同理论、过往普遍认知以及相关研究结论。逐空解题时优先定位上下文的提示线索，比如前后文的原词复现、动作搭配逻辑、指代/转折关系，结合鸟类生存的常识排除不符合语境的选项，最后代入所有选项通读验证，确保语篇通顺、逻辑自洽。
【解析】
1. 前文提到“只要起得足够早，根据你居住的地点，你大概率能听到鸟儿悦耳的鸣叫”，说明该现象在很多地方十分常见，A奇怪的、B特别的、C简单的均不符合语境，选D common。
2. 前文提到晨鸣最早凌晨4点就开始，结合常识清晨时段不可能持续数天、数周、数月，因此是持续数小时，选B hours。
3. 后文提到“其他鸟类远离它们的领地”，鸟类鸣叫的目的之一是警示同类不要入侵领地，A warn警告符合语境，B记忆、C教授、D帮助均不符合逻辑。
4. 此处说明能见度低让鸟类很难开展其他生存活动，结合鸟类的生存行为，对应的活动是寻找食物，B searching for寻找符合语境，A等待、C想到、D查看均不符合。
5. 前文提到能见度低很难觅食，因此鸟类就转而选择鸣叫，instead表示“取而代之、反而”完全契合逻辑，选C。
6. 前文明确出现了“One theory is that...”的表述，对应此处的另一个理论，选B theory，和前文形成原词呼应。
7. 句意为鸟类在野外生存并不容易，wild表示野外，符合鸟类的自然生存环境，A建筑、B天空、D房屋均不符合场景。
8. 前文提到鸟类通过欢快鸣叫展示自身状态，说明它们平安度过了充满生存挑战的夜晚，safely安全地符合语境，选B。
9. 句意为清晨更凉爽干燥的空气，让鸟儿的鸣叫声可以清晰传播，allow sth to do表示“使得……能够做某事”，符合固定搭配和语义，选D。
10. 鸣叫声清晰传播的目的是让其他鸟类分辨出附近是谁在鸣叫，nearby附近的符合语境，选D。
11. 后文原词复现提示“The songs didn't travel farther”，此处表示声音可以传播更远的距离，travel符合声音传播的常用表达，选B。
12. 此处指代前文提到的“鸣叫声能传播更远”的普遍观点，用指示代词this，选A。
13. 研究人员做对照实验，分别在清晨和正午播放提前录制的麻雀的录音，recordings录音符合实验场景，选A。
14. 前文说鸣叫声并没有传播得更远，后文说它们的连续性更好，前后分句是转折关系，用but，选A。
15. 句意为鸟类的鸣唱能量有限，所以它们选择在自己的叫声最有可能被其他鸟类听到的时段鸣叫，chance表示机会，the best chance of being heard即被听到的最佳概率，完全契合语境，选C。
【答案】
1.D 2.B 3.A 4.B 5.C 6.B 7.C 8.B 9.D 10.D 11.B 12.A 13.A 14.A 15.C
【知识点】
语境推断，词义辨析，逻辑关系判断
【点评】
本题属于自然生态主题的科普类完形填空，话题趣味性强，多数题目都有明确的上下文线索提示，既考查学生对核心词汇的词义掌握，也锻炼学生结合语篇逻辑推理判断的能力，学生做题的同时还能了解鸟类晨鸣的相关科普知识，难度设置合理，适合中等水平的学生练习。
【难度系数】
0.6