题目内容：

To the untrained eye it might seem like just a bit of a monkey trick. But when Milly the mandrill (山魈, 西非洲产的大狒狒) covers her face with her hand she is actually sending a serious message to her fellows: “Leave me alone!”

Experts believe the 15-year-old mandrill invented the gesture to warn other monkeys at Colchester Zoo to give her some space. And, surprisingly, the signal has been picked by other members of the group, who use it when they too require solitude.

Biologist Mark Laidre believes the behavior is evidence of social culture among the mandrills. Importantly, the sign language is unlikely to have been influenced by human activities because mandrills do not copy humans. Mr. Laidre expects further research will uncover other monkeys using cultural gestures — the ability to communicate with the hands in a meaningful way. “By covering their eyes with their hands, possibly conveyed to others that they wanted to be left alone and this message may have been respected as a ‘do not disturb’ sign,” said Mr. Laidre.

While the hand is in place, other monkeys are not likely to approach or touch the monkey. Those who rank lower in the social order also use the technique to avoid attacks from more powerful group members. As the discovery appears to be unique to Colchester Zoo, it suggests it is a local phenomenon that arose naturally in the community of 25 mandrills.

Curator （园长） Sarah Forsyth said: “We believe Milly made up the signal and over the past five years some of the younger mandrills have picked it up. We’re not sure why she started doing it but it could be as simple as ‘I can’t see them, so they can’t see me’. It really does show you how intelligent mandrills are.”

1. What’s the text mainly about?

A. How humans influenced monkeys.

B. A monkey invented a gesture.

C. A new social culture was discovered.

D. How experts made the new discovery.

2. What does the underlined word “solitude” in the second paragraph mean?

A. Aloneness.       B. Comfort.

C. Protection.      D. Respect.

3. According to Mark Laidre, _____.

A. human activities affect mandrills’ sign language

B. animals are slow in picking up information

C. mandrills’ social culture has nothing to do with humans

D. mandrills are the largest species of monkey in the world

4. The monkeys can also use the “do not disturb” sign to _____.

A. protect themselves from being harmed

B. struggle against more powerful group members

C. show humans how intelligent they are

5.What can be known from the text?

A. Milly invented the gesture when she was 15.

B. Mandrills are best known for their social ability.

C. Why Milly first used the sign language is known to experts.

D. Only the mandrills in Colchester Zoo use the gesture.