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问题 单项选择题

下列关于质点的说法中，正确的是（）

A.质点一定是体积很小、质量很小的物体

B.地球虽大，且有自转，但有时仍可将地球看作质点

C.研究跳高运动员的起跳和过杆动作时，可以把运动员看成质点

D.研究花样滑冰运动员的冰上动作时，能把运动员看成质点

答案

参考答案：B

解析：A、质量、体积很小的物体不一定能看成质点，如原子的质量很小、体积很小，在研究原子内部结构的时候是不能看成质点的；错误B、研究地球公转时，地球的形状和大小对研究的问题没有影响，所以地球可以看做质点；正确C、研究跳高运动员的起跳和过杆动作时，看成质点就看不到动作了；错误D、研究花样滑冰运动员的冰上动作时，看的就是运动员的优美的动作，所以此时的运动员不能看成是质点；错误故选B

填空题


A patrol team of sea lions and dolphins featured in a large-scale military exercises being conducted by the U. S. and its allies in the Pacific Ocean. The machine (1) took part in simulated mine recovery and mine detection missions during the biennial Rim of the Pacific Exercise (RIMPAC) war games. The (2) started on June 19 and will run (3) Friday.
"There are a number of mechanical systems that work in those areas. (4) high-tech gadgets deployed by the military can’t (5) the natural skills of dolphins and lions," said Tom Lapuzza, spokesman for UN Navy’s Marine Mammal Program. Sea lions have "incredible good underwater (6) " and can dive down to 300 meters to catch a recovery line to a mine, he said. Dolphins use sonar to (7) mine.
Human beings have a long (8) of training animals to join the military. Horses have been the most widely-used animals (9) the recorded history of (10) . In early times, horses were used to (11) chariots or to (12) armored forces. With the development of modem weapons and motorized (13) , the use of horses for military purposes fell into (14) . (15) , horses were still used (16) by the German army during World War II for transporting (17) and equipment, including artillery.
During World War II, (18) with explosives strapped to their backs were used as anti-tank weapons. In other (19) , they were used for detecting mines. Some dogs were also used as messengers.
Other animals have also (20) in the military. Recorded history shows the use of elephants for military purposes as early as 1,100 B. C.. They were employed during World War II by both the Japanese army and the (21) .
There are records showing that over 100,000 reindeer were used by Finland to tow sleds during World War II. They carried the (22) to hospitals, brought supplies to the troops and moved heavy anti-tank weapons. It is well documented that oxen have been (23) used in war as improvised beasts of burden. During World War II, spiders were employed by the Allies to spin silk for (24) in cross-hairs on bomb scopes and other optical instruments. People also are finding that Vampire bats’ ability to use echolocation is very interesting as we (25) to learn how it works and it may benefit the army.
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单项选择题

男孩，18个月。自幼以人工喂养，食欲低下。半小时前突然面色苍白，神志模糊。体检：营养发育差，腹部皮脂消失，唤之无反应，呼吸间有暂停，脉搏 60/min。

对本例的饮食治疗，以下列哪项最为正确

A．开始每天用30～40kcal/kg，渐增至每天 100～120kcal/kg

B．开始每天用40～50kcal/kg，渐增至每天 110～120kcal/kg

C．开始每天用40～60kcal/kg，渐增至每天 120～150kcal/kg

D．开始每天用50～60kcal/kg，渐增至每天 130～150kcal/kg

E．开始每天用60～80kcal/kg，渐增至每天 140～160kcal/kg
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