题目内容：

Squirrels often communicate with whistles, chirps and chucks, which sound like the word “chuck”. Whistles and chirps are like the sounds that many birds make. Now scientists have translated some of their squirrel-speak.

Hare, a professor of zoology at the University of Maniloha in Winnipeg, and his team managed to record squirrels' alarm calls. The researchers studied the sounds and then played them back to 60 wild squirrels, which the scientists approached individually with a video recorder to capture(抓拍）their responses. Some squirrels lifted their heads up and became alert(警惕的）. Creatures that were more frightened simply ran for their lives and dived into caves.

"In effect then, whistles that mix with chucks say 'there's an enemy of average threat that's here', and whistles without chucks say 'there's an enemy of seemingly average threat around here somewhere', while pure chirps say, 'I'm hiding here because there's an immediate danger. ' " Hare told. Discovery News.

Hare and some other researchers believe such sounds are part of an advanced language that develops just as all other communication systems.

Although squirrels risk their lives when they call out to warn others of threats, other squirrels might admire this behavior, thus increasing the caller’s social status, like humans who look up to heroes. Hare added that other animals, such as birds, probably understand at least some squirrel language, since they also may benefit from the alarm calls.

In fact, another Canadian study found that deep-voiced, black-capped chickadees have their own language too. According to certain research, there are a lot of tidings in chickadees' calls, such as directing fellows' activities, keeping in contact between mates, and raising alarms.

While chickadees and other birds are often welcomed into gardens by homeowners, squirrels are frequently viewed as pests(害兽）. Hare wishes a greater understanding of the complex social lives and communication systems of squirrels will provide “hope that humans will gain a greater appreciation and stop doing harm to these animals”.

1.The text mainly talks about _______ .

A. the ways for squirrels to escape from their enemies

B. the comparison between squirrels and chickadees

C. the calling for the protection of squirrels

D. the study on the language of squirrels

2.If a squirrel is in a very dangerous situation, it would probably make ____.

A. whistles with chucks   B. pure chirps

C. whistles without chucks D. repeated chucks

3.The underlined word “tidings” in paragraph 6 probably means ____.

A. difficulties B. noises

C. messages         D. languages

4.What can be learned from this text?

A. Squirrels communicate with each other as humans do.

B. Some squirrels understand the recorded alarm calls.

C. Other animals also well understand the language of squirrels.

D. Birds such as chickadees don’t have their own language.