题目内容
2008年以来，索马里附近海域先后发生累计逾120起的海盗劫船事件。海盗为何如此猖獗甲、乙、丙、丁四人有如下断定： 甲：海盗猖獗的主因是被劫船只的船主通常都愿支付高额赎金。 乙：如果海盗猖獗的主因是被劫船主愿支付高额赎金，那么肯定会助长海盗的气焰。 丙：确实助长了海盗的气焰，但其主因并非被劫船主都愿支付高额赎金。 丁：海盗猖獗主要是被劫船主愿支付高额赎金，但其嚣张气焰并非都由此生成。 上述如果只有一个人的断定是真的，那么以下断定都不可能真，除了：
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数列6，a，b，16，前3项成等差数列，后3项成等比数列． (1)4a+b=0． (2)a，b是x2+3x-4=0的两个根．
The molecules of carbon dioxide in the Earth"s atmosphere affect the heat balance of the Earth by acting as a one-way screen. (1)_____ these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concerned, to pass (2)_____, they absorb some of the longer-wave-length, infrared emissions radiated from the Earth"s surface, radiation that would (3)_____ be transmitted back into space. For the Earth to maintain a constant average temperature, such emissions from the planet must (4)_____ incoming solar radiation. If there were no carbon dioxide in the atmosphere, heat would (5)_____ from the Earth much more easily. Today, (6)_____, the potential problem is too much carbon dioxide. Could the increase in carbon dioxide (7)_____ a global rise in average temperature, and could such a rise have serious (8)_____ for human society Mathematical models that allow us to calculate the rise in temperature as a function of the increase (9)_____; that the (10)_____ is probably yes. One mathematical model (11)_____ that doubling the atmospheric carbon dioxide would raise the global mean surface temperature by 2.5℃. This model assumes that the atmosphere"s relative humidity remains constant and the temperature decreases with altitude at a (12)_____ of 6.5℃ per kilometer. The assumption of constant relative humidity is important, because water vapor in the atmosphere is another (13)_____ absorber or radiation at infrared wavelengths. Because warm air can hold more (14)_____ than cool air, the relative humidity will be constant (15)_____ the amount of water vapor in the atmosphere increases (16)_____ the temperature rises. (17)_____, more infrared radiation would be absorbed and reradiated (18)_____ to the Earth"s surface. The resultant warming at the surface could be expected to melt snow and ice, (19)_____ the Earth"s reflectivity. More solar radiation would be absorbed, (20)_____ to a further increase in temperature.
有红、蓝、黄、白、紫五种颜色的皮球，分别装在五个盒子里，甲、乙、丙、丁、戊五人猜测盒子里皮球的颜色。甲：第二盒是紫的，第三盒是黄的。乙：第二盒是蓝的，第四盒是红的。丙：第一盒是红的，第五盒是白的。丁：第三盒是蓝的，第四盒是白的。戊：第二盒是黄的，第五盒是紫的。猜完之后打开盒子发现，每人都只猜对了一种，并且每盒都有一个人猜对。 如果上述断定都为真，以下哪项也一定是真的（）
甲、乙两人沿着圆形跑道匀速跑步，它们分别从直径AB两端同时相向起跑．可以确定圆形跑道的总长为460m． (1)第一次相遇时离A点100m． (2)第二次相遇时离B点60m．
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