题目内容：

    Putting a dinosaur skeleton（骨架）together is not easy. The skeletons are usually very incomplete. Many dinosaur fossils（化石） are discovered badly damaged. Bones are often found crashed (压碎) or bent by the great weight of the dirt and rock above. Sometimes parts from different creatures are mixed together. This just adds to the confusion.

Unfortunately, some scientists have not been careful enough in their descriptions of dinosaurs. They have told grand stories of how dinosaurs looked and behaved. All of these descriptions are based on guesswork – the imaginations of people who have never seen a living dinosaur. Some scientists have made complete pictures of dinosaurs based on just a single bone or tooth or leg. Such pictures are based on many guesses and very little facts. The scientists' ideas often turn out to be wrong when more facts are discovered.

Dinosaur fossils are not found with labels attached showing what the animals looked like. That is why no pictures of dinosaurs are exactly right. Every dinosaur painting is sure to contain at least some wrong information. No artist in the twentieth century ever saw the living, breathing animals -- complete with skin, flesh, and color.

For instance, imagine never having seen or heard of a peacock. One day you find the jumbled bones of it buffed in the ground. You try to put the bones together to form a skeleton. And then you try to draw a picture of what the animal looked like when it was alive. But bones cannot tell the whole story. Even if you are a very good artist, it would be a miracle if you drew a tree picture of a peacock just from the bones and your imagination.

1.Which of the following is NOT a reason why putting a dinosaur skeleton together is difficult?

A.No one has seen a living dinosaur.

B.Dinosaur bones are too complicated when found.

C.Dinosaur bones are crushed or bent when found.

D.Dinosaur bones are mixed with other animals' bones when found.

2.According to Paragraph 2, we can infer that _______.

A.the descriptions of dinosaurs contain some wrong information

B.some scientists are very careful in their descriptions of dinosaurs

C.some scientists have made complete pictures of dinosaurs based on facts

D.the ideas of scientists are often proved wrong when more facts are discovered

3.Taking a peacock as an example, the author shows that________

A.it is easy to put the peacock bones together to form a skeleton

B.it is not easy to put the peacock bones together to form a skeleton

C.a very good artist can draw a good picture even if he has never seen a peacock

D.it is impossible to draw a correct picture based on the bones and one's imagination

4.What is the passage mainly about?

A.Why it is difficult for scientists to find dinosaur fossils.

B.How we can get right information about dinosaurs.

C.Why scientists can't give exact description of dinosaurs.

D.How we can put a dinosaur skeleton together.