热门试题:
[判断题]戴无菌手套的原则是:未戴手套的手只允许接触手套外面,已戴手套的手则不可触及未戴手套的手或另一手套的内面。( )
A.正确
B.错误
[单选题] 在路基地面排水设备中,排水沟用来排除()的水流。
A.地表
B.路堤坡面
C.地表及路堤坡面
D.路堑上
[单选题]依据《安全生产法》的规定，国家对严重危及生产安全的工艺、设备实施（ ）制度。
A.审批
B.登记
C.淘汰
D.监管
[单选题]采气树上能在紧急情况下自动关闭的平板阀,通常称为( )。
A.节流阀
B.手动平板阀
C.液动平板阀
D.安全阀
[单选题]耳蜗微音器电位的功能主要是
A.感音换能作用
B.维持身体平衡
C.传导声波
D.引起位置觉
E.听觉和前庭反应
[判断题] 消防员大檐帽饰带不用时应当拉紧并保持水平;大檐帽松紧带不用时,应当拉紧并水平置于后侧帽墙;卷檐帽松紧带不使用时,不得露于帽外
A.正确
B.错误
[单项选择]石基础施工技术要求，砌筑时，应双挂线，分层砌筑，每层高度为( )，大体砌平。
A. 10～20cm
B. 20～30cm
C. 30～40cm
D. 40～50cm
[不定项选择题]共用题干
Lack of Oxygen Delayed the Rise of Animals on Earth
Scientists have long speculated as to why animal species didn't flourish sooner,once sufficient oxygen covered the Earth's surface. Animals began to prosper at the end of the Proterozoic period,about 800 million years ago-but what about the billion-year stretch before that,when most researchers think there also was plenty of oxygen?
Well,it seems the air wasn't so great then,after all.
In a study published Oct. 3 1 in Science,Yale researcher Noah Planavsky and his colleagues found that oxygen levels during the"boring billion"period were only 0.1%of what they are today .In other words,Earth's atmosphere couldn't have supported a diversity of creatures,no matter what genetic advancements were poised to occur.
"There is no question that genetic and ecological innovation must ultimately be behind the rise of animals,but it is equally unavoidable that animals need a certain level of oxygen,"said Planavsky,colead author of the research along with Christopher Reinhard of the Georgia Institute of Technology.“We're providing the first evidence that oxygen levels were low enough during this period to potentially prevent the rise of animals."
The scientists found their evidence by analyzing chromium(Cr)isotopes in ancient sediments from China,Australia,Canada,and the United States.Chromium is found in the Earth's continental crust,and chromium oxidation is directly linked to the presence of free oxygen in the atmosphere.
Specifically,the team studied samples deposited in shallow,iron-rich ocean areas,near the shore.They compared their data with other samples taken from younger locales known to have higher levels of oxygen.
Oxygen's role in controlling the first appearance of animals has long vexed scientists."We were missing the right approach until now,"Planavsky said."Chromium gave us the proxy."
Previous estimates put the oxygen level at 40%of today's conditions during pre-animal times. leaving open the possibility that oxygen was already plentiful enough to support animal life.
In the new study,the researchers acknowledged that oxygen levels were"highly dynamic"in the early atmosphere,with the potential for occasional spikes. However,they said,"It seems clear that there is a first-order difference in the nature of Earth surface Cr cycling"before and af- ter the rise of animals.
"If we are right,our results will really change how people view the origins of animals and other complex life,and their relationships to the co-evolving environment,"said co-author Tim
Lyons of the University of California-Riverside."This could be a game changer."
"There's a lot'of interest right now in a broader discussion surrounding the role that environ- mental stability played in the evolution of complex life,and we think our results are a significant contribution to that,"Reinhard said.
The samples studied in the research were collected in ocean areas.
A.Right
B.Wrong
C.Not mentioned
[填空题]使用车梯进行作业时，应指定（），工作台上的人员不得超过两名。
[单项选择]对开放式问题与封闭式问题的优势与风险看法不正确的是（）
A. 前者浪费时间，后者节省时间
B. 前者搜集信息全面，后者搜集信息不全面
C. 前者谈话不容易控制，后者容易控制谈话内容
D. 前者谈话气氛紧张，后者谈话氛围愉快
[多选题]党的作风,关系( )。
A.党的形象
B.党的未来
C.人心向背
D.党的生命
E.党的命运
三、判断题
[判断题]加在电阻上的电流或电压增加一倍,功率消耗是原来的四倍。
A.正确
B.错误
[单项选择]扣件式钢管脚手架上螺栓的松紧度必须适度，要求扭力矩最大不超过（）。
A. 3ｋｇ.ｍ
B. 4ｋｇ.ｍ
C. 5ｋｇ.ｍ
D. 6ｋｇ.ｍ
[单项选择]Passage TwoAccording to the speaker,what can the present-day robots do
A. Drive cars.
B. Fly planes.
C. Pay wages.
D. Repair machines.
[单选题]建筑工程的发包单位( )将建筑工程的勘察、设计、施工、设备采购一并发包给一个工程总承包单位。
A.不得
B.可以
C.应当
D.必须
[单选题]现场常用的指重表,其结构中含有()。
A.快绳固定器和传感器
B.死绳固定器和传感器
C.死绳指重器和显示仪
D.快绳固定器和显示仪
[单选题]现场勘察由工作票签发人或（）组织。
A.项目经理
B.工作负责人
C.生产管理人员
D.工作许可人
[单项选择]安徽宣城的道地药材是
A. 山楂
B. 木瓜
C. 五味子
D. 桃仁
E. 补骨脂
[单选题]轨道电路的状态分为调整状态、（ ）状态、断轨状态。
A.断路
B.开路
C.分路
D.短路
[单项选择]存在潮汐周日不等的海区，一个太阴日里相邻两次高潮中潮高较低的高潮称为（）。
A. 高高潮
B. 高低潮
C. 低高潮
D. 低低潮
[单选题]诊断原发性肝癌常用肿瘤标志物的最佳组合是
A. AFP、γ-GTⅡ、ALP
B. AFP、γ-GT、GST
C. γ-GTⅡ、ALP1、 GST
D. AFP、γ-GT、TPS
E. AFP、CA19-9、NSE
[单选题]焊接过程中，产生在焊条和零件之间的( )将焊条和零件局部熔化，受电弧力作用，焊条端部熔化后的熔滴过渡到母材，和熔化的母材融合一起形成熔池，随着焊工操纵电弧向前移动，熔池金属液逐渐冷却结晶，形成焊缝。（中）
A.电弧
B.温度
C.压力
D.气体
[单项选择]电气工具和用具应由专人保管，每（）应由电气试验单位进行定期检查。
A. 3个月
B. 6个月
C. 9个月
D. 12个月
[多选题]无缝线路地段应根据( )，合理安排作业项目。
A.季节特点
B.锁定轨温
C.线路状态
D.钢轨温度
[判断题]某次事件，造成该市人民政府有关部门确定的二级重要电力用户电网侧供电全部中断，根据《国家电网有限公司安全事故调查规程》（国家电网安监〔2020〕820号），该起事件为六级电网事件。
A.正确
B.错误
[单选题]采购合同由分公司( )对项目部相关人员进行合同交底。
A.合同管理员
B.采购管理员
C.内业员
D.物资部经理
[单选题].中间站一般在列车到站前( )开始检票。
A.10min
B.20min
C.30min
D.40min
[单项选择]
Awarded the Nobel Prize for physics in 1918, German physicist Max Planck is best remembered as the originator of the quantum theory. His work helped usher in a new era in theoretical physics and revolutionized the scientific community’s understanding of atomic and subatomic processes. Planck introduced an idea that led to the quantum theory, which became the foundation of twentieth century physics. In December 1900, Planck worked out an equation that described the distribution of radiation accurately over the range of low to high frequencies. He had developed a theory which depended on a model of matter that seemed very strange at the time. The model required the emission of electromagnetic radiation in small chunks or particles. These particles were later called quantums. The energy associated with each quantum is measured by multiplying the frequency of the radiation, v, by a universal constant, h. Thus, energy, or E, equals by. The constant, h, is known as Planck’s
A. radical
B. extremist
C. momentous
D. militaristic
[单选题]依据下列哪项可诊断为葡萄胎：（ ）
A.出现甲状腺功能亢进现象
B.停经8周子宫14周妊娠大
C.停经12周后妊娠反应加剧
D.停经8周后出现不规则阴道流血
E.停经8周后阴道内排出血液中有串珠水泡
[多项选择]一般装卸搬运技术装备的特点是（）。
A. 适应性和作业能力强
B. 适应性和作业能力弱
C. 机动性强
D. 机动性较弱
E. 安全可靠
[单选题]数据库管理系统是( )。
A.操作系统的一部分
B.在操作系统支持下的系统软件
C.一种编译系统
D.一种操作系统
[单选题]货物实际运到日数的计算：起算时间从承运人（ ）起算。
A.承运货物的次日
B.指定装车日期的当日
C.承运货物的当日
D.制票完毕
[多项选择]EVDO0的关键技术有（）。
A. 前向时分复用
B. 比例公平调度算法
C. HybriD.ARQ
D. 反向信道增强
[单项选择]属抗贫血药物的是（）
A. 氯喹
B. 左旋咪唑
C. 右旋糖酐铁
D. 阿苯达唑
E. 肾上腺素
[单选题]1.51 持有B2驾驶证的，如果具有注销最高准驾车型情形之一的，降级后的准驾车型为_____。
A.C1
B.C1M
C.C2
D.C2M
