Up to the present, many scientists have made great contributions to the understanding of the universe.
One of them is Albert Einstein, a German physicist, who revolutionized our concepts of space and time with his theories of relativity. In 1905 Einstein published his special theory of relativity. The foundation of the theory is the observation that light moves at a constant speed as measured by all observers, whatever its state of motion. One consequence is that measurements of distance and time are not absolute quantities but very relative to the motion of an observer. Another is that energy(E) can be converted into mass(m), and vice versa, according to the formula E=mc2 ,where c is the speed of light. Ten years later, Einstein’s general theory of relativity extended this work to include acceleration and gravity — stating that the two are equivalent. Einstein showed that gravity is actually the warping of space by matter. One consequence is that l
| Not too many decades ago it seemed
"obvious" both to the general public and to sociologists that modern society has
changed people’s natural relations, loosened their responsibilities to kin and
neighbors, and substituted in their place superficial relationships with passing
acquaintances. However, in recent years a growing body of research has revealed
that the "obvious" is not true. It seems that if you are a city resident, you
typically know a smaller proportion of your neighbors than you do if you are a
resident of a smaller community. But, for the most part, this fact has few
significant consequences. It does not necessarily follow that if you know few of
your neighbors you will know no one else. Even in very large cities, people maintain close social ties within small, private social worlds. Indeed, the number and q A. did not have the same interests as their neighbors B. could not develop long-standing relationships C. tended to be associated with bad behavior D. usually had more friends [单项选择]中药制剂中一般杂质的检查包括（）
A. 酸、碱、固形物、重金属、砷盐等 B. 酸、碱、浸出物、重金属、砷盐等 C. 酸、碱、氯化物、重金属、砷盐等 D. 酸、碱、挥发油、重金属、砷盐等 E. 酸、碱、土大黄苷、重金属、砷盐等 [单选题] 卫生法律文件的效力范围( )
A.只包括时间效力 B.只包括空间效力 C.只包括对象效力 D.以上三种效力都包括 E.以上都不对 [单项选择]（）是情绪产生的基础。
A. 动机 B. 需要 C. 行为 D. 认知 [判断题]减温器一般分为表面式和混合式两种。
A.正确 B.错误 [单选题]值班处警统计搜索条件的( )单选、违规类型默认是一级超速、二级超速、禁止抽烟、禁止接打电话、生理疲劳、三级超速、6种,可多选,时间默认显示当天。
A.公司 B.时间区间 C.驾驶员 D.车辆 [单项选择]统一命令原则是指（）。
A. 每人只能有一个上司 B. 权责对等 C. 责任不可委任 D. 反映组织系统的互关系 [单项选择]高钾血症常表现为：
A. 肠鸣音减弱 B. 心肌兴奋性增高 C. 肠麻痹 D. 心肌应激性下降 E. 呼吸困难 [单选题]（ ）为C类一般事故。
A.向占用区间发出列车 B.调车冲突 C.施工耽误列车 D.列车相撞 [判断题]国际联盟和英、美等国对日本侵华的行动采取姑息纵容的政策。
A.正确 B.错误 [判断题]瓦斯检查工的仪器坏了,应立即出井更换仪器,更换仪器后下井照常工作。()
A.正确 B.错误 [单选题]重组DNA技术中常用的工具酶下列哪项不是( )
A.限制性核酸内切酶 B.反转录酶 C.DNA聚合酶I D.DNA连接酶 E.RNA聚合酶 [单项选择]三焦为
A. 元神之府 B. 玄府 C. 血之府 D. 孤府 E. 髓之府 [单选题]数据库的并发操作可能带来的问题包括（ ）
A.增强数据独立性 B.非授权访问 C.丢失修改 D.增加数据冗余度 我来回答: 提交
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