B
Sometimes, we can discover human history in surprising places. Not long ago, scientists in Spain found over 200 human-made items in ancient bearded vulture nests(巢穴). Surprisingly, the oldest item is about 700 years old. This discovery shows how nature can preserve(保存) human history in unexpected ways.
Bearded vultures are large birds and usually live in areas with mountains. Although they eat small animals, their main(主要的) food is animal bones(骨头). They break bones into smaller pieces by dropping them from great heights. These birds used to be common in southern Spain. But because of hunting and modern farming practices, no bearded vultures live in the area now.
The nests of bearded vultures are special because the birds have a habit of using them over and over again. Scientists searched for these old nests. To find them, they studied many historical records to learn where the birds once lived in the area. Finally, they found 12 ancient nests built long ago. Once they discovered the nests, they studied everything inside. As expected, they found lots of bones. However, to the scientists' great surprise, there were quite a lot of human-made things. The birds probably brought the items back to build their nests.
This discovery makes protecting bearded vultures even more important. Today, there are only a few thousand left in the wild. Scientists are working hard to help their number grow.

(
B
)49. How did the scientists find the old nests?
A. They discovered them by accident.
B. They studied historical records.
C. They followed living bearded vultures.
D. They used modern tools to search for them.
(
C
)50. Bearded vultures kept the human-made items because
.
A. they were very playful
B. the items smelled like bones
C. they wanted to make their nests better
D. they gave the items to their babies as gifts
(
D
)51. From the passage, we cannot find the answer to the question “
”.
A. How many human-made items did scientists find in the nests?
B. How old is the oldest human-made item found in the nests?
C. How many bearded vulture nests did scientists study?
D. How old is the oldest bone found in the nests?
(
C
)52. What is probably the best title for this passage?
A. Bearded vultures have unusual eating habits
B. Scientists work hard to protect bearded vultures
C. Bearded vulture nests carry historical surprises
D. Scientists get to know more about bearded vultures
