Unlike buried treasure and some minerals, fossils are usually not valuable in themselves. However, most of the fossils you find will be of greatest value to you. They will help you learn much about the geologic history of the earth and its inhabitants.
If it were not for fossils, we would have no way of knowing about the animals that once roamed the earth or that once crawled on the bottom of the ancient seas. In fact, we would not even know for sure that there were once seas in some regions if it were not for the many fossils of sea animals that we find there.
You can look at some fossils and see for yourself the shape of the ancient animals. Even if you collect only bits of one kind of fossil, you may still be able to tell what it looked like. Making sense out of fossil bits is a little like working a jigsaw puzzle. Sometimes you will lose pieces, but you can still recognize the picture and even use your imagination to fill in missing details. The habits of ancient sea animals are not so easy to determine. Therefore, scientists study the structure and the habits of similar living animals to learn what the ancient ones must have been like. There are some things, however, that neither the study of fossils nor the study of living animals can tell us. For example, no one knows what colour most ancient sea animals were. Also, since the soft parts disappeared soon after death, many details of their internal structure are unknown. So the pictures of ancient sea creatures (as well as dinosaurs!) are what scientists think the animals looked like. Reconstructing the life of an ancient sea animal on the basis of fossil evidence and the characteristics of similar living animals is a little like relying on circumstantial evidence in court.
1. This passage is mainly about animals that __________.
A. have very tough hides
B. once lived on the earth
C. inhabit the seas of today
D. are becoming extinct
2. With the help of fossils we can __________.
A. reconstruct life of the past
B. predict the future
C. explain the changes of the seasons
D. save some species of animals from extinction
3. Many details of ancient animals are lacking because __________.
A. many species have not been found
B. volcanic disasters have permanently buried many fossils
C.many fossils lie in deep water and cannot be recovered
D. soon after death the soft parts of the body decay
49. To “determine" in the passage is closest in meaning to __________.
A. come across
B. study
C. find out
D. imitate
50. This passage implies that a scientist's evaluation of the past is based on __________.
A. laboratory experiments with live animals
B. a few facts mixed with a lot of opinions
C. predictions made in the past and present
D. field studies of our society
