题目内容

Mark Twain’s letter about the Statue of Liberty ______.

A. represented a serious question as to the need for the statue
B. was a put-on by a journalist
C. raised a great deal of money
D. poked fun at the French

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If you want to stay young, sit down and have a good think. This is the research finding of a team of Japanese doctors, who say that most of our brains are not getting enough exercise—and as a result, we are aging unnecessarily soon.Professor Taiju Matsuzawa wanted to find out why otherwise healthy farmers in northern Japan appeared to be losing their ability to think and reason at a relatively early age, and how the process of aging could be slowed down.With a team of colleagues at Tokyo National University, he set about measuring brain volumes of a thousand people of different ages and varying occupations.Computer technology enabled the researchers to obtain precise measurements of the volume of the front and side sections of the brain, which relate to intellect (智能) and emotion, and determine the human character. (The rear section of the brain, which controls functions like eating and breathing, does not contract with age, and one can continue living without intellectual or emotional faculties.)Contraction of front and side parts—as cells die off—was observed in some subjects in their thirties, but it was still not evident in some sixty- and seventy-year-olds.Matsuzawa concluded from his tests that there is a simple remedy to the contraction normally associated with age—using the head. The findings show in general terms that contraction of the brain begins sooner in people in the country than in the towns. Those least at risk, says Matsuzawa, are lawyers, followed by university professors and doctors. White collar workers doing routine work in government offices are, however, as likely to have shrinking brains as the farm worker, bus driver and shop assistant. Matsuzawa’s findings show that thinking can prevent the brain from shrinking. Blood must circulate properly in the head to supply the fresh oxygen the brain cells need. “The best way to maintain good blood circulation is through using the brain,” he says, “Think hard and engage in conversation. Don’t rely on pocket calculators.” The team of doctors wanted to find out ().

A. why certain people age sooner than others
B. how to make people live longer
C. the size of certain people’s brains
D. which people are most intelligent

What does "Pay yourself first" refer to

A. Take more education and make yourself promoted quickly.
B. When you get your paycheck, save some portion of it.
C. Lend money from bank when you want to prepare for the future.
D. Accumulate money by all means.

了解什么使种群发生同步波动很重要,因为同步对灭绝风险、食物链稳定性和影响一个生态系统的其他因素都有明显效应。相似的捕食者一猎物循环中所涉及的相邻种群经常发生同步振荡,David Vasseur和Jeremy Fox利用理论及实验室缩微环境发现,当捕食者存在时,猎物种群之间的扩散是造成这种相位锁定(相位同步)的原因。扩散是不同生物(Vasseur和Fox所研究的动物是雪兔和加拿大猞猁)从一个分离的种群向另一个转移的能力。由这项工作所获得的模型对于代表捕食者一猎物和宿主一病原体系统的参数的大范围变化都是可靠的,说明它可能具有普遍适用性。 给本段文字选择一个恰当的标题( )。

A. 生态系统中的同步波动
B. 种群扩散的意义
C. 种群同步波动探秘
D. 生态系统新发现

甲、乙两公司拟签订一项货物买卖合同,甲为卖方,乙为买方,标的物为A种货物。在签订合同时甲要求丙公司为乙付款提供保证,当乙不能付款时,由丙连带承担偿付货款的责任。考虑到乙经营情况良好,丙同意提供保证并与甲签订了书面保证合同。甲、乙两公司的货物买卖合同签订后,甲以不能全部提供合同标的物为由,与乙协商将标的物改为B种货物。甲、乙双方达成改变合同标的物协议,未经丙同意。甲在约定的供货时间内仍然不能提供全部B种货物。甲未经乙同意,与丁公司达成协议,不足部分的B种货物由丁向乙提供。甲、丁向乙提供了全部货物,但超过了甲、乙约定的供货期限。乙虽接受了货物,但以甲、丁未按期履行供货义务为由,行使先履行抗辩权,拒绝履行付款义务。甲遂诉至人民法院,请求判令丙偿还货款。请回答下列问题: 乙行使先履行抗辩权是否合法?( )

A. 不合法,因为乙已经接受了货物
B. 合法,因为甲迟延履行合同
C. 合法,因为合同并不是由甲完全履行的
D. 不合法,乙只能履行支付货款的义务

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