题干

下列关于匀强电场中场强和电势差的关系,正确的说法是(  )

A:在相同距离上的两点,电势差大的其场强必定大

B:任意两点间的电势差,等于场强大小和这两点间距离的乘积

C:沿着电场线方向,任何相等距离上的电势降落必相同

D:电势降落的方向必是场强方向

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答案(点此获取答案解析)

C

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60年代初,西德已实现经济奇迹,迫切需要开辟国外市场和改善国际地位,加之中苏分歧公开化,西德上下出现了积极发展对华关系的呼声。1964年5月,双方驻瑞士的外交机构就发展两国关系问题首次进行官方接触,但由于各种原因未取得实质性结果。70年代初,随着中美关系大门的打开和中国在联合国合法席位的恢复,以及西德同苏联、东欧关系逐步正常化,中国与西欧国家建交出现高潮,以基民盟主席施特劳斯为首的西德对苏强硬派一再试探与中国发展关系,同时西德各界要求同中国建交的呼声也日益高涨。1972年尼克松访华之后,在野的基民盟要求联邦政府同中国建交,基民盟领导人之一,时任联邦议院外委会主席施罗德提出了访华愿望。勃兰特政府也向中方发出了愿与中国谈判建交的信息。1972年7月,施罗德主席应邀访华,是新中国成立后来访的首位西德重要政治家。施在与周总理的谈话中表示,两国关系正常化的时机已经成熟,联邦政府和在野党都主张两国就建交问题进行谈判。乔冠华副外长以外交学会副会长的名义与施罗德主席共同签署内部谅解,声明两国政府都有早日建交的愿望,并商定通过双方驻第三国的外交代表进行必要的准备工作。这份谅解为两国通过谈判正式建交外交关系奠定了基础。1972年10月11日,中国外交部长姬鹏飞与联邦德国外长谢尔一起,在北京人民大会堂举行了只有15分钟的签字仪式,双方正式签署了中德建交公报。

——据《百度百科》整理

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    Airbags, now found in almost every vehicle, have saved countless lives and largely reduced the severity of injuries in crashes. Similar technology could greatly reduce broken hips (髋部) resulting from a fall, something most seniors fear.

    Dr. Robert Buckman and his start-up company, Active Protective in Allentown, Pennsylvania, has developed a promising solution, a wearable airbag that can protect hip bones in the event of a fall. The idea was the result of Dr. Buckman's years as a doctor at Temple University. He noticed how many elderly people were being brought into hospitals with broken hip due to falls, and how they often never completely recovered from the injuries. He started to ask what he could do for these people, and that was when he started trying to figure out whether there was a way of helping people who were at the highest risk of falling and suffering these kinds of injuries.

    The device is worn much like a regular belt, but on the outside of the clothing, and it includes sensors that monitor the movement of hips. If the device detects that the person, is falling, an airbag opens before the person hits the ground, cushioning the fall. When the wearer hits the ground, the bag reduces the force to the hip bones by 90 percent, enough to avoid the majority of hip injuries.

    With one out of every three people aged 65 and older suffering serious falls each year, Active Protective has a big market for its wearable device. It also has the potential to sizably reduce hip - related health care expenses: Hip injuries among the elderly cost the US health care system in 2012 $30 billion, which doesn't include the long-term care expenses associated with the high percentage of patients that can no longer live independently.