题目内容：

Humans have uniquely expressive faces. We laugh, we cry, we turn red with feeling. Now, scientists report that blue-and-yellow macaws(金刚鹦鹉) may join us in this club of emotions – at least,when it comes to blushing.

Parrots are known for being clever and chatty. They ' re even skilled enough to make their own tools and occasionally nose their way into human machines like cars. Their curiosity and courage are what make them excellent pets. So it ' s no surprise that they have their own range of communication tools. On the whole, birds are no strangers to blushing. Many different kinds of birds have been known to exhibit this hehavior. Parrot owners often notice it in their pets. The motivations behind it are still a mystery to scientists , though.

To zero in on why macaw faces blush,some scientists led by Aline Bertin of the University of Tours studied five captive blue-and-yellow macaws as they interacted with each other and their human caretakers. They were amazed to see that human attention seemed to make the macaws blush. The blushing died down when the caretakers ignored the parrots.

Facial expressions can be signs of a human ' s emotional state. Likewise, bird blushing could convey well-being. It' s not quite as  obvious as  smiling. Still, it ' s fairly impressive. After all, these macaws don' t have the same facial muscles that we do. The birds are much smarter and kinder than they look. They are believed to be as intelligent as monkeys.

Bertin and the other scientists believe their work opens the door to further research. One limitation of the study is that no macaws in natural environment have been observed. That makes it hard to draw conclusions about the birds as a species. They are also not quite sure what the blushing means. There is still more to learn about these possible expressions of emotion.

1.Which  of the  following best explains" captive" in paragraph 3 ?

A. Unique.    B. Talkative.

C. Curious.    D. Caged.

2.Birds might blush_____________.

A. when people ignore them .    B. to show they are happy.

C. to show they are hungry .    D. when something upsets them.

3.What is TRUE about scientists ' reaction to macaws blushing?

A. They are puzzled by how birds can communicate with one another.

B. They are motivated to continue studying how macaws express emotion.

C. They are curious about why other birds are unable to convey emotion.

D. They are interested to study monkeys to see if they blush as strongly.

4.What is the main idea of the text?

A. Parrots make excellent pets.

B. Parrots are skilled to make tools.

C. The macaws can communicate with each other.

D. The macaws can go red in the face with feeling.