更多"An ecosystem is a group of animals "的相关试题:
[多项选择]Many animals and plants threatened with extinction could be saved if scientists spent more time talking with the native people whose knowledge of local species is dying out as fast as their languages are being lost.
Potentially vital information about many endangered species is locked in the vocabulary and expressions of local people, yet biologists are failing to tap into this huge source of knowledge before it is lost for good, scientists said. "It seems logical that the biologists should go and talk to the indigenous people who know more about the local environment than anyone else," said David Harrison, an assistant professor of linguistics at Swarthmore College in Pennsylvania.
"Most of what humans know about ecosystems and species is not found in databases or libraries or written down anywhere. It’s in people’s heads. It’s in purely oral traditions," Dr. Harrison told the American Association for the Advancement of Science in San Francisco. "About 80 per cent of the ani
[单项选择]It is animals and plants which lived in or near water whose remains are most likely to be preserved, for one of the necessary conditions of preservation is quick burial, and it is only in the seas and rivers, and sometimes lakes, where mud and silt have been continually deposited, that bodies and the like can be rapidly covered over and preserved.
But even in the most favorable circumstances only a small fraction of the creatures that die are preserved in this way before decay sets in or, even more likely, before scavengers eat them. After all, all living creatures live by feeding on something else, whether it be plant or animal, dead or alive, and it is only by chance that such a fate is avoided. The remains of plants and animals that lived on land are much more rarely preserved, for there is seldom anything to cover them over. When you think of the innumerable birds that one sees flying about, not to mention the equally numerous small animals like field mice and voles which you
A. a large number of remains
B. a number of remains
C. only a small number of remains
D. few remains
[填空题]Unlike most plants, animals are living beings that have the ability to move{{U}} (11) {{/U}}in search of food.
Scientists divide animals into two groups. The animals in the first group are those with backbones{{U}} (12) {{/U}}the second group includes those without{{U}} (13) {{/U}}.
Birds, fish and mammals belong to the first group. Among them, animals are{{U}} (14) {{/U}}the most complex animals. Mammals have{{U}} (15) {{/U}}or fur. They nurse their young.{{U}} (16) {{/U}}people use the word "animal" when they are talking about mammals such as the dog, cat, cow, horse, rabbit or{{U}} (17) {{/U}}.
Most animals of the second group{{U}} (18) {{/U}}in water because the pull of gravity makes it difficult for them to{{U}} (19) {{/U}}about on land.
The largest animal on earth is the blue whale. A whale often grows more than 30 meters{{U}} (20) {{/U}}and weighs more than 100 tons. The elephant is the largest land animal and the ostrich is the largest bird.