To fight a noise by making more noise
sounds strange, but that’s exactly what motor engineers are doing in Germany and
some other countries. Carmaker’s research and development laboratories have already proved that mixing more noise with the help of loudspeakers can reduce the unwanted noise. Physicists have known about the technique for a long time. Sound is made up of pressure waves in the air. If two sound waves of the same frequency (频率) mix so that the highest point of one wave happens at the same time as the lowest point of the other wave, the result is no sound. Therefore, by producing a perfect copy of the noise and delaying it by half a wave cycle (周期), we can kill the unwanted noise. Using this technique many carmakers are racing to develop noise killing systems (系统) both inside and outside the cars. Another good t A. make a car lighter B. make a car quieter C. reduce the cost of a silencer D. improve the performance of a silencer [不定项选择题]患者,男,55岁,2小时前进食苹果后突发大呕血2次,呕吐呈喷射状,量达1000ml左右,为新鲜血。体格检查:T37℃,P98次/分,R22次/分,Bp100/67mmHg。巩膜稍黄染,双手呈肝掌样变。肝未触及,脾肋下1cm,无肌紧张及反跳痛,移动性浊音阳性。
护士接诊时最适宜为该患者取下列哪一体位
A.俯卧位 B.端坐位 C.去枕平卧位 D.头低脚高位 E.中凹卧位 [单选题]在轨检车波形图中,()指左(右)股钢轨顶面沿轨道纵向的凹凸不平。
A.高低 B.轨向 C.水平加速度 D.垂直加速度 [单选题]编制人工定额时,应计入定额时间的是( )。
A.工人在工作时间内聊天时间 B.工人午饭后迟到时间 C.材料供应中断造成的停工时间 D.工作结束后的整理工作时间 [单选题]列车牵引时不需要下列哪些指令( )。
A.载荷信息 B.轮径数据 C.零速信号 D.级位信息 [单项选择]Atoms (原子) are all around us. They are the bricks of which everything is made. Millions of atoms are held in just one grain of salt, but in spite of their small size they are very important. The way an everyday object acts depends on what kind of atoms are in it and how they act.
For example, you know that most solid objects melt (熔化) if they get hot enough. How does it happen It is the effect of the heat on the object’s atoms. All atoms move constantly. When they are hot, they move faster. Usually the atoms in an object hold together and give the object its shape. But if the object grows hot, its atoms move so fast that they break the force that usually holds them together. They move out of their usual places so that the object loses its shape. Then we say that the object is melting. Atoms in an object move ______ . A. all the time B. whenever it is hot C. when it is melted D. when it is heated [多选题]在对变电站计算机监控系统进行检验前应做充分的准备,( )、检修工具等是其必须具备的内容。
A.图纸资料 B.备品备件 C.测试仪器 D.测试记录 [单选题]一般地,我们在电路中使用二极管主要是利用( )。
[1分] A.放大特性 B.单向导电特性 C.恒温特性 D.恒流特性 [单项选择]微机产品至今已经历了多次演变,其主要标志是( )。
A. 体积与重量 B. 用途 C. 价格 D. 微处理器的字长和功能 [判断题]施工现场的主要道路必须进行硬化处理,裸露的场地和集中堆放的土方应采取绿化、覆盖、固化等控制扬尘、改善景观的措施。( )
A.正确 B.错误 [简答题]谈谈宪法序言的功能。
[单选题] 将汽车电气设备用规定的电气图形符号作原理性的电路连接所绘制的电路图形称为汽车( )。
A.布线图 B.电路原理图 C.线束图 D.电气示意图 [多项选择]局部或全身应用耳毒性药物,其致聋的途径包括()。
A. 血液循环 B. 脑脊液 C. 迷路窗膜 D. 胎盘 E. 以上都是 [填空题]对插有“限速连挂”表示牌的车辆,在溜放连挂时不得超过( )km/h。
[判断题]电灯突然暗淡并维持,用电线路有电感性大负荷退出。
A.正确 B.错误 [单选题]随着城市的不断发展,出现了越来越多的名称同名、同音、谐音,方言发音相同或相似的道路,这些易混淆道路名称以及环线、环路的出现,接警调度员在()时应通过询问行政区划、周边道路等方式加以区分。
A.接警 B.力量调派 C.地址定位 D.GPS定位 [判断题]财务专项检查工作程序分为准备、实施、报告、整改落实、归档五个阶段。( )
A.正确 B.错误 [简答题]LBE50203零序保护的I、II、III、Ⅳ段的保护范围是怎样划分的?
[判断题](43823)( )在区间或站内线路、道岔上封锁施工作业时,车站行车室设驻站联络员,施工地点设现场防护员。
A.正确 B.错误 [多项选择]下列选项中,关于江南传统水乡的描述,正确的是( )。
A. 传统民居粉墙黛瓦,朴素淡雅 B. 民居的单体形式比较简单和程式化 C. 具有文脉久远、布局独特、水乡风情、物产丰富的特点 D. 多为三合或四合式楼房布局 E. 西塘为典型的江南水乡 [多选题]某建设单位在灭火器安装设置后对建筑内灭火器进行配置验收,发现如下情况:1)楼内的灭火器配置点数量不足,不能满足配置场所的任一点都在灭火器设置点的保护范围内;2)灭火器设置在托架上,灭火器中心距地高度为1.5m;3)托架设有夹持带,夹持带的开启方式无法从正面看到;4)部分灭火器配置点灭火器数量不足;5)部分灭火器设置点位于走道柱内侧,并未设置指示灭火器位置的发光标志;下列关于该次验收的说法,正确的有( )。
A.有严重缺陷项2项 B.有重缺陷项2项 C.有轻缺陷项2项 D.该建筑灭火器配置不能通过验收 E.该建筑灭火器配置应通过验收 [填空题]{{B}}Passage Two{{/B}}
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