题目内容
Since Fisher's time, it has been realized that genes can sometimes influence the chromosome or gamete in which they find themselves so that the gamete will be more likely to participate in fertilization. If such a gene occurs on a sex-determining (X or Y) chromosome, then highly aberrant sex ratios can occur. But more immediately relevant to game theory are the sex ratios in certain parasitic wasp species that have a large excess of females. In these species, fertilized eggs develop into females and unfertilized eggs into males. A female stores sperm and can determine the sex of each egg she lays by fertilizing it or leaving it unfertilized. By Fisher's argument, it should still pay a female to produce equal numbers of sons and daughters. Hamilton, noting that the eggs develop within their host—the larva of another insect—and that the newly emerged adult wasps mate immediately and disperse, offered a remarkably cogent analysis. Since only one female usually eggs in a given larva, it would pay her to produce one male only, because this one could fertilize all his sisters on emergence. Like Fisher, Hamilton looked for an evolutionarily stable strategy, but he went a step further in recognizing that he was looking for a strategy.
The author suggests that the work of Fisher and Hamilton was similar in that both scientists ______.
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Section B
Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice.
The current emergency in Mexico City that has taken over our lives is nothing I could ever have imagined for me or my children. We are living in an environmental crisis, an air-pollution emergency of unprecedented severity. What it really means is that just to breathe here is to play a dangerous game with your health.
As parents, what terrorizes us most are reports that children are at higher risk because they breathe more times per minute. What more can we do to protect them and ourselves？ Our pediatrician's medical recommendation was simple, abandon the city permanently. We are foreigners and we are among the small minority that can afford to leave. We are here because of my husband's work. We are fascinated by Mexico its history and rich culture. We know that for us, this is a temporary danger. However, we cannot stand for much longer the fear we feel for our boys. We cannot stop them from breathing.
But for millions, there is no choice. Their lives, their jobs, their Futures depend on being here. Thousands of Mexicans arrive each day in this city, desperate for economic opportunities. Thousands more are born here each day. Entire families work in the streets and practically, live there. It is a familiar sight: as parents hawk goods at stoplights, their children play in the grassy highway dividers, breathing exhaust fumes. I feel guilty complaining about my personal situation; we won't be here long enough for our children to form. the impression that skies are colored only gray.
And yet the government cannot do what it must to end this problem. For any country especially a developing Third World economy like Mexico's, the idea of barring from the capital city enough cars, closing enough factories and spending the necessary billions on public transportation is simply not an option. So when things get bad, as in the current emergency, Mexico takes half measure a prohibiting some more cars from circulating stopping some factories from producing that even its own officials concede aren't adequate.
The word "emergency" implies the unusual. But when daily life itself is an emergency the concept loses its meaning. It is human nature to try to adapt to that which we cannot change. Or to mislead ourselves into believing we can adapt.
According to the passage, the current emergency in Mexico City refers to ______.
A．Dates and names that cannot be verified.B．Unusual works of art.C．Articles written by
It used to be the case that if you left your car in the sun on a hot summer's day, then getting back in again afterwards was agony. Not any more. Now you press your key into the door lock and the car's air-conditioning system automatically starts cooling the interior. You just have to wait a minute before you get in.
That is just one of the newer gimmicks that make the modem car so much more comfortable to drive than those produced not so long ago. Another innovation is the self-adjusting seat. When you put the key in the car door, the front seat will automatically adjust itself to the driver's preferred driving position.
These ideas were dreamt up at General Motors' research laboratories in Detroit. The laboratory was set up in the mid-sixties, in response to consumer groups who attacked the company for its safety record. Since then, the company has set itself an impossible goal: that you'll be able to walk away from most car accidents. It spends roughly one billion US dollars every year on safety research.
The company is working on helping drivers survive crashes at higher speeds. The idea is that the driver won't fly out of the car because of his seat belt, He won't be crushed by the side door coming in because it will be strengthened by a side beam. His ribs won't be crushed, nor his organs injured by the steering wheel, because it will bend when the body hits it. His face won't be slashed by broken glass because the windscreen won't shatter.
Every year, the total world-wide bill for injuries of all types is estimated at US $ 500 billion. Transport injuries of all sorts account for one quarter of this. This gives some indication of the size of the problem the scientists working at General Motors' research laboratory have set themselves.
"Not any more." in paragraph one indicates that ______.
A．To get a good job.B．To earn more money.C．To show her ability to others.D．To learn mo
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