故选B项。 C Around the globe far more bird species are losing ground than gaining, according to an expansive review of a half-century of bird population research published in the journal Annual Review of Environment and Resources in May. The review, entitled The State of the World's Birds,...
T hese peoples settled at first in sca ttered hunting-and-gathering bands, although in some places near lakes and rivers, people who fished, with a more secure food supply, lived in larger population concentrations. Agriculture seems to have reached the se people from the Near East, since ...
Originally moths were uniformly pale gray or whitish in color; dark-colored (melanic) individuals were rare and made up less than 2 percent of the population. [#highlight1]Over a period of decades, dark-colored forms became an increasingly large fraction of some populations and eventually came...
They first became more widely distributed in the southern part of Manitoba, and by the 1940s were abundant throughout its southeastern portion. In the 1950s their population swelled in Canada. The control of coyotes in the prairie region in the 1950s may have been a factor in raccoon ...
Plants, and particularly microorganisms, have a far greater capacity for individual modification than do animals. Natural selection is involved even in this phenomenon, since the capacity for nongenetic adaptation is under strict genetic control. When a population shifts to a new specialized environment...
B. population ageing is a hard problem, but it needs to be solved urgently C. people are too busy to solve the population ageing problem D. much time and effort will be lost in solving the ageing problem Passage 2 Questions 6 to 10 are based on the following passage: ...
Agriculture will release less And, a diet bad for human beings, it seems, is also bad for the greenhouse gas than transportation in the future.environment. As the world's population grows, experts say more C. Our change in diet has nothing to forests and tropical areas will become farmland...
It could be, too, that warfare became a competitive response to population growth and to the increasing scarcity of [#highlight9]prime[/highlight9] agricultural land, and that it played an important role in the emergence of the Mayan states. [#paragraph6][#highlight11]Now that we know ...
This period was followed by a time of decline in the Maori population and a societal transition to smaller, less numerous settlements. The apparent decline fits the pattern expected as a consequence of the Maori’s overexploitation of moa. [#paragraph6]Finally, the Maori introduced the Polynesian...
840, people had aggregated into villages in favorable settings because of their competitive organizational advantages over smaller units in the face of growing population and depletion of local wild resources. Hence, the very nature of the initial slash-and-burn agriculture encouraged a further ...