△ABC中，已知（a+b+c）（b+c-a）=bc，则A的度数等于（ ） A．1

设60≤a≤84  28≤b≤33，求：a+b，a-b．

同一地区水体中氯化物含量是相当恒定的，当其含量突然增加时，有下列哪些可能（）

A.生活污水污染

B.工业废水污染

C.农田径流污染

D.人畜粪便污染

E.生物性污水污染

玻璃纤维的制造工艺有（）

A、坩埚法拉丝和池窑漏板法

B、气相法

C、有机纤维法

销售部的网号是 (1) ，广播地址是 (2) ；技术部的网号是 (3) ，广播地址是 (4) ；每个子网可用的IP地址有 (5) 个。

（1）处填（）

At some point during their education, biology students are told about a conversation in a pub that took place over 50 years ago. J. B. S. Haldane, a British geneticist, was asked whether he would lay down his life for his country. After doing a quick calculation on the back of a napkin, he said he would do so for two brothers or eight cousins. In other words, he would die to protect the equivalent of his genetic contribution to the next generation.

The theory of kin selection--the idea that animals can pass on their genes by helping their close relatives--is biology’s explanation for seemingly altruistic acts. An individual carrying genes that promote altruism might be expected to die younger than one with "selfish" genes, and thus to have a reduced contribution to the next generation’s genetic pool. But if the same individual acts altruistically to protect its relatives, genes for altruistic behavior might nevertheless propagate.

Acts of apparent altruism to non-relatives can also be explained away, in what has become a cottage industry within biology. An animal might care for the offspring of another that it is unrelated to because it hopes to obtain the same benefits for itself later on (a phenomenon known as reciprocal altruism). The hunter who generously shares his spoils with others may be doing so in order to signal his superior status to females, and ultimately boost his breeding success. These apparently selfless acts are therefore disguised acts of self interest.All of these examples fit economists’ arguments that Homo sapiens is also Homo economicus--maximizing something that economists call utility, and biologists fitness. But there is a residuum of human activity that defies such explanations: people contribute to charities for the homeless, return lost wallets, do voluntary work and tip waiters in restaurants to which they do not plan to return. Both economic rationalism and natural selection offer few explanations for such random acts of kindness. Nor can they easily explain the opposite: spiteful behavior, when someone harms his own interest in order to damage that of another. But people are now trying to find answers.

When a new phenomenon is recognized by science, a name always helps. In a paper in Human Nature, Dr Fehr and his colleagues argue for a behavioral propensity they call "p reciprocity". This name is intended to distinguish it from reciprocal altruism. According to Dr Fehr, a person is a p reciprocator if he is willing to sacrifice resources to be kind to those who are being kind, and to punish those who are being unkind. Significantly, p reciprocators will behave this way even if doing so provides no prospect of material rewards in the future.

It can be inferred from Paragraph 4 that（）

A.Human behavior is confined to the exclusive concern of psychologists

B.Economists’ utility is only the explanations for random acts of kindness

C.Altruism is developed during the long process of human evolution

D.Biologists can help economists explain some human behavior deviations