由于海洋的天然屏障,与陆地防务相比,在广阔的海上拥有基地,可大大减少战时所用守备兵力,只要掌握了海上运输线,就可以以最机动的方式集中最优势兵力在海外某一区域实施作战。而在陆地取得每个军事胜利都得部署大量守备兵务以巩固成果,海上同等数量的部队,比陆地使用起来会更加高效。 这段文字表明的主旨是( )。
A. 海上防务较陆地防务简单
B. 陆地防务集中优势兵力作战的机动性不足
C. 陆上军事胜利需要巩固,海上军事胜利不用
D. 海军作战能力较陆军作战能力强
现代文学学科很大程度被用来阐释现代革命的合理性。某些作家在现代文学史上实际的影响很大,但在建构现代文学这门学科时,人们或者对他们进行批判,或者进行回避,或者进行歪曲,这样就使他们的面貌在教科书和读书界里起起伏伏,沉浮不定。 这段话直接支持的观点是( )。
A. 现代文学学科强调革命的合理性
B. 现代文学学科在作家的取舍和评价上带有功利性
C. 文学史对作家的取舍和评价较为客观
D. 教科书和读书界对作家有不同的评价标准
Text 3In the angry debate over how much of IQ comes from the genes that children inherit from parents and how much comes from experiences, one little fact gets overlooked: no one has identified any genes (other than those in the case of retardation) that affect intelligence. So researchers led by Robert Plomin of London’s Institute of Psychiatry decided to look for some.Plomin’s colleagues drew blood from two groups of 51 children each. They are all White living in six counties around Cleveland. In one group, the average IQ is 136. In the other group, the average IQ is 103. Isolating the blood cells, the researchers then examined each child’s chromosome 6 ( One of 23 human chromosomes along which genes made of DNA). Of the 37 landmarks on chromo- some 6 that the researchers looked for, one jumped out: a form of gene called IGF2R occurred in twice as many children in high-IQ group as in the average group -- 32 percent versus 16 percent. The survey concludes that it is this form of the IGF2R gene, called allele 5, that contributes to intelligence.Plomin cautions that "this is not a genius gene. h is one of many." ( About half the differences in intelligence between one person and another are thought to reflect different genes, and half reflect different life experiences. ) The gene accounts for no more than four extra IQ points. And it is neither necessary nor sufficient for high IQ: 23 percent of the average-IQ kids did have it, but 54 percent of genius kids did not.The smart gene is known by the interesting name "insulinlike growth factor 2 receptor" (IGF2R to its fun). It lets hormones like one similar to insulin dock with cells. Although a gene involved with insulin is not the most obvious candidate for an IQ gene, new evidence suggests it might indeed play the role. Sometimes when a hormone docks with the cell, it makes the cell grow; sometimes it makes the cell commit suicide. Both responses could organize the development of the brain. Scientists at the National Institutes of Health find that insulin can stimulate nerves to grow. And in rat brains, regions involved in learning and memory are chock full of insulin receptors.Even though this supports the idea that IGF2R can affect the brain and hence intelligence, some geneticists see major problem with the IQ-gene study. One is the possibility that Plomin’s group fell for what’s called the chopsticks fallacy. Geneticists might think they’ve found a gene for chopsticks skill, but all they’ve really found is a gene more common in Asian than, say, Africans. Similarly, Plomin’s IQ gene might simply be one that is more common in groups that emphasize academic achievement. "What if the gene they’ve found reflects ethnic differences" asks geneticist Andrew Feinberg of Johns Hopkins University. "I would take these findings with a whole box of salt." Some geneticists don't accept the IGF2R gene-study because()
A. the subjects are not selected according to certain standards.
B. the subjects are totally different people.
C. the findings have not been copied by other researchers.
D. the subjects are from groups emphasizing one particular aspect.