五、阅读理解
When autumn arrives in the United States and Canada, you can see one of nature's greatest scenes—the yearly migration(迁徙) of the monarch butterflies(帝王蝶).
No other butterfly in the world migrates(迁徙) like the orange and black monarchs of North America. They cannot live for long periods in cold weather. For this reason, each autumn around October, the butterflies from Canada travel up to 3,000 kilometres south to spend the winter in warmer locations. Some even fly to the mountains of Mexico. There are so many of them that they almost block out the sky. You can even hear their wings beating.
It usually takes the butterflies two months to reach the south of Mexico. After spending five months there, they head back north in the spring. They lay eggs along the way and die. Three generations of butterflies will live and die during the spring journey. The fourth and final generation of the year is born in early autumn and will reach the north. But the butterflies hardly get to rest before starting the long journey south again to Mexico.
The most amazing thing about these butterflies is that they return to the very same trees in Mexico that their great-great-grandparents used the winter before.
However, the population of this colourful butterfly has dropped in recent years. In 2015, the US Fish and Wildlife Service said that nearly a billion monarchs had disappeared from the overwintering sites(越冬地点) since 1990, reported the Washington Post. One of the main reasons, experts say, is that farmers have used herbicides(除草剂) on plants that the monarchs' larvae(幼虫) live and feed on.
()1. When do monarch butterflies travel south?
A. In autumn. B. In spring. C. In winter. D. In summer.
()2. Why do monarch butterflies fly to the south every autumn?
A. To find suitable places to lay eggs.
B. To avoid the strong winds in the north.
C. To look for a warmer place to live.
D. To look for new types of food sources.
()3. What can we know according to the passage?
A. The butterflies spend two months staying in the south of Mexico.
B. In the south, the butterflies will all stay on one tree.
C. The butterflies that fly back to the north are not the same ones that flew to the south.
D. The butterflies will get to rest before starting the long journey south again to Mexico.
()4. What is the main idea of the passage?
A. The harm of farm herbicides to monarch butterflies.
B. Special winter homes of monarch butterflies in Mexico.
C. The way monarch butterflies finish their round-trip journey.
D. The migration of monarch butterflies and the dangers they face.

1. A 2. C 3. C 4. D

【分析】
本题为英语阅读理解题，需先通读全文把握帝王蝶迁徙的时间、原因、过程及面临的问题，再针对每个问题回到原文定位对应信息，逐一分析选项排除错误答案，确定正确选项。
【解析】
1. 第1题：根据原文第二段“each autumn around October, the butterflies from Canada travel up to 3,000 kilometres south”可知，帝王蝶南迁时间为秋天，故选A。
2. 第2题：原文第二段提到帝王蝶无法长时间在寒冷天气生存，因此南迁是为了到更温暖的地方过冬，故选C。
3. 第3题：A项错误，原文提到帝王蝶在墨西哥南部待五个月而非两个月；B项错误，原文仅说它们会回到墨西哥相同的树，并非全部待在同一棵树；C项正确，春天北迁的帝王蝶产卵后死亡，三代死亡后第四代才是当年秋天北迁的，故北迁的不是之前南迁的同一批；D项错误，原文提到它们几乎没休息就再次南迁，故选C。
4. 第4题：全文先介绍帝王蝶的迁徙过程，后说明其数量下降的现状及原因（除草剂影响），主旨为帝王蝶的迁徙和面临的危险，故选D。
【答案】
1.A 2.C 3.C 4.D
【知识点】
英语阅读理解、细节理解题、主旨大意题
【点评】
本题围绕帝王蝶迁徙展开，考查学生快速定位原文信息、理解细节及概括主旨的能力，文本逻辑清晰，需学生精准对应原文内容，难度适中。
【难度系数】
0.6