A security camera(安防摄像头) in a Mexican city filmed something bad. Hundreds of yellow-headed blackbirds fell from the sky. They fell onto the ground like a black cloud. Most birds flew away but some of them stayed on the streets and they died.  

No one really knows what happened to the animals. Some people say that dirty air killed those birds. Others say that the animals are killed by electricity(电) because they stand on power lines. And also many people believe that there is a predator. They say another bigger animal want to have those birds as food. So it chases the birds to the ground to make a catch. However, the true reason is still a mystery(谜).

Bird lovers say those birds stay in the US and Canada in summer. They fly to Mexico for winter. It’s warmer there.

1.This event probably happens in _________.

A the US

B Canada

C Mexico

D Australia

解析：选C。C 细节理解题。根据第一段“A security camera(安防摄像头) in a Mexican city filmed something unusual. ”可知，该事件发生在墨西哥。故选C。

2.What did people find on the streets?

A A black cloud.

B Dead birds.

C Flying birds.

D Nothing.

解析：选B。B 推理判断题。根据第一段最后一句“Most birds flew away but some of them stayed on the streets and they died. ”可知，一些鸟停留在街上，它们死了，可知街上有死鸟。故选B。

3.What does the underlined word “predator” mean in Chinese?

A 哺乳动物.

B 爬行动物.

C 飞行动物.

D 食肉动物.

解析：选D。D 词义猜测题。根据该词所在句的后一句 “They say another bigger animal want to have those birds as food.”可知是另一个较大型的动物想要吃这些鸟，由此推断predator是捕食的食肉动物。故选D。

4.What season is it now?

A Spring.

B Summer.

C Autumn.

D Winter.

解析：选D。D 推理判断题。根据第一段可知该事件发生在墨西哥。根据最后一段的“They fly to Mexico for winter. ”可知鸟儿们冬天飞往墨西哥。由此可推断现在是冬季。故选D。

5.The text is probably from_______.

A a textbook

B a newspaper

C a story book

D a history book

解析：选B。B文章出处题。 根据全文内容可知，本文主要报道了墨西哥发生一起“黄头黑鹂集体死亡事件”，文章属于新闻类稿件，应刊载在报纸上。故选B。