[单项选择]A series of research projects in recent years have looked at the small, spiny, marine invertebrate known as the sea urchin. The sequence of their genetic code has been successfully analyzed, revealing a remarkably close resemblance to that of humans. This provides a firmer foundation for the claim that humans and sea urchins share a common ancestor, which must have lived over 540 million years ago.
The red sea urchin, found off the West coast of North America and elsewhere, was considered a pest in the 1960s and attempts were made to eradicate them wherever locals were farming kelp. In the 1970s, though, American sea fisheries discovered a lucrative market in Japan, where certain internal organs of these creatures were considered a delicacy, and by the 1990s they had become one of the most valuable marine resources.
There are implications for these fisheries in the latest findings about the way sea urchins mature. Not only are the invertebrates capable of reaching an age of 2
A. lose their ability to reproduce
B. do not suffer from the effects of ageing
C. start to show a slight reduction in size
D. are more easily attacked by other marine animals

[单项选择]A series of research projects in recent years have looked at the small, spiny, marine invertebrate known as the sea urchin. The sequence of their genetic code has been successfully analyzed, revealing a remarkably close resemblance to that of humans. This provides a firmer foundation for the claim that humans and sea urchins share a common ancestor, which must have lived over 540 million years ago.
The red sea urchin, found off the West coast of North America and elsewhere, was considered a pest in the 1960s and attempts were made to eradicate them wherever locals were farming kelp. In the 1970s, though, American sea fisheries discovered a lucrative market in Japan, where certain internal organs of these creatures were considered a delicacy, and by the 1990s they had become one of the most valuable marine resources.
There are implications for these fisheries in the latest findings about the way sea urchins mature. Not only are the invertebrates capable of reaching an age of 2
A. Rotting animal matter.
B. Tetracycline.
C. Microscopic animal life.
D. Kelp.

[单项选择]Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing. Consequently more than 100 cities in the United States still have levels of carbon monoxide, particulate matter, and ozone (generated by photochemical reactions with hydrocarbons from vehicle exhaust) that exceed legally established limits. There is a growing realization that the only effective way to achieve further reductions in vehicle emissions--short of a massive shift away from the private automobile—is to replace conventional diesel fuel and gasoline with cleaner-burning fuels such as compressed natural gas, liquefied petroleum gas, ethanol, or methanol.
All of these alternatives are carbon-based fuels whose molecules are smaller and simpler than those of gasoline. These molecules burn mom cleanly than gasoline, in part because they have fewer, if any, carbon-carbon bonds, and the hydrocarbons they do emit are
A. countering a flawed argument that dismisses a possible solution to problem
B. reconciling contradictory points of view about the nature of a problem
C. identifying the strengths of possible solutions to a problem
D. discussing a problem and arguing in favor of one solution to it