热门试题:
[单项选择]在Access中已建立了“雇员”表,其中有可以存放照片的字段。在使用向导为该表创建窗体时,“照片”字段所使用的默认控件是______。
A. 图像框
B. 绑定对象框
C. 非绑定对象框
D. 列表框
[单项选择]吸收操作中,减少吸收剂用量,将引起尾气浓度()。
A. 升高
B. 下降
C. 不变
D. 无法判断
[单选题]下列化验项目中,哪个属于常规化验项目()。
A.元素分析
B.透光率
C.粘结指数
D.结渣性
[单项选择]以下人物中,不属于竹林七贤的是()。
A. 张角
B. 阮籍
C. 嵇康
D. 刘伶
[单选题]坚持一个中国原则,是两岸关系和平发展的(丿O
A.政治基础
B.必然要求
C.根本原则
[判断题]耐温800℃以上的保温材料称作耐火材料。( )
A.正确
B.错误
[多选题]多选题厂房应定期检查,厂房的结构应无( )等现象,门窗应完整。
A.倾斜
B.裂纹
C.风化
D.下塌 "
[多项选择]思想教育要善于运用哪些方法()
A. 群众参与。
B. 平等讨论。
C. 自我教育。
D. 批评和自我批评。
[单项选择]随着工业化、城镇化的不断推进,我国的流动人口数量不断增多。据2011年4月公布的第六次全国人口普查主要数据,目前我国不包括市辖区内人户分离的流动人口约为()亿人。
A. 2.1
B. 3.2
C. 2.21
D. 2.5
[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.
Tim Lyons liked to play computer games in his spare time.
A.Right
B.Wrong
C.Not mentioned
[多选题]除使用特殊仪器外,所有使用携带型仪器的测量工作,均应在()进行。
A.电流互感器的二次侧
B.电流互感器的一次侧
C.电压互感器的二次侧
D.电压互感器的一次侧
[判断题]设备资源信息配置文件格式遵循《电网设备通用模型数据命名规范》(GB/T 33601)的要求,可根据实际配置修改。
A.正确
B.错误
[单选题]( )和硬币补币箱钥匙原则上不允许单独借给AFC维修人员,维修需要硬币补币箱钥匙时需车站人员陪同,或者将补币箱内现金全部清空后由AFC维修人员单独维修。
A.纸币回收箱钥匙
B.钱箱钥匙
C.纸币补币箱钥匙
D.硬币回收箱钥匙
[简答题]【HH】 汽轮机通流部分结垢对其有何影响?
[判断题]依据《江苏省建设工程费用定额》(2014 年)规定,建筑物使用通风面积在 20000 ㎡以上的通风工程为一类工程。( )
A.正确
B.错误
[判断题]LKJ-2000运行监控记录装置,参数设定操作,在机车运行或停车时均可操作。
A.正确
B.错误
[判断题]机动车通过施工作业路段时,应当注意警示标志,快速通过。( )
A.正确
B.错误
[单选题]由部分电路欧姆定律R=U/I和R=ρL/S可知( )。
A.导体的电阻与两端加的电压成正比
B.导体的电阻与流其中的电流成反比
C.导体的电阻与电压、电流无关
D.导体的电阻与流其中的电流成正比
[单选题]公安机关深入开展健康教育的目的不包含:( )
A.引导公安民警牢固树立健康生活的理念
B.增强执法办案水平
C.积极开展文体活动,陶冶情操,增强体质
D.丰富业余文化生活
[单选题]空气自然冷却的熔化焊机,周围空气最高温度不大于( )℃。
A.50
B.45
C.40
[单项选择]九味羌活汤和川芎茶调散组成中均含有的药物是()
A. 羌活、川芎
B. 麻黄、甘草
C. 黄芩、甘草
D. 羌活、白芷
E. 荆芥、白芷
[简答题]人民检察院拒绝受理原审人民法院移送的案卷材料,其做法是否正确
[多选题]对于供电企业查获得窃电者,下列说法正确的是( )。
A.应予制止并可当场中止供电
B.应收集具有法律效应的证据
C.窃电者应所窃电量补交电费,并承担补交电费三倍的违约使用电费
D.拒绝承担窃电责任的,供电企业应报请电力管理部门依法处理
[单选题]276、下路指示牌标注为 “G104 孙耿 大桥镇 出口101”的收费站是(___)。
A.A、阳信
B.B、济阳
C.C、靳家
D.D、遥墙
[单项选择]患者女性,28岁。自诉外阴瘙痒、白带增多。怀疑有滴虫病,取阴道分泌物镜检可见滴虫活动,治疗一般可用()
A. 甲硝唑
B. 替硝唑
C. 青霉素
D. 依米丁
E. 氯喹
[单选题]㠋动车组SKS1故障时,如果断开控制空开( ) 时 ,会造成故障车牵引丢失,GFX-3A 无法正常工作,需要司机手动过分相。
A.24-F11
B.24-F12
C.24-F13
D.24-F14
[单选题]细胞内液和组织液是通过内环境进行物质交换的,体液的各个部分之间既是彼此隔开的,又是相互联系的,细胞浸浴在组织液中,在细胞内液与组织液之间只隔着细胞膜,水分和一切能够进出细胞膜的物质,都可以在细胞内液与组织液之间进行交换,在组织液与血浆之间只隔着毛细血管壁,水分和一切能够透过毛细血管壁的物质,都可以在组织液与血浆之间进行交换。
对此下列理解正确的是:
A.体液的各个部分都可以进行物质交换
B.体液之间的物质交换有选择性
C.细胞膜阻隔着体液之间的流动
D.毛细血管壁可以实现一切物质的自由交换
[单选题]卷扬机在作业中( )不得跨越正常作业的卷扬钢丝绳。
A.任何人
B.非操作人员
C.非施工管理人员
D.非本项目体的人员
[判断题]井下高压电气设备的修理和调整工作,应有工作票和施工措施。( )
A.正确
B.错误
[简答题]A manual worker probably earns more money than a man who does mental labor. For example, a brick-layer can earn more money than his next door neighbor who is a university professor. Yet, white-collar workers still have a higher reputation and social position than blue-collar workers even though they have lower pay.
[单项选择]下列各项中,除哪项外均可作为热痹辨证的依据()
A. 关节疼痛,局部灼热红肿
B. 关节疼痛,得冷稍舒
C. 发热、恶风、口渴
D. 关节痠痛、游走不定
E. 舌红、苔黄、脉滑数
[判断题]为提高办事效率, 不必每一份文件都经过领导签发。 ( )
A.正确
B.错误
[判断题]调试司机必须根据调试负责人的要求安全操纵电动客车、工程车。凡是需要动车时,需要与车辆段(场)调度员(车辆段(场))或行车调度员(正线)联系落实运行进路的安全并得到其同意,确认行车“三要素”正确后方可动车。( )
A.正确
B.错误
[多选题]62. 对于因( )带电线路、设备导致检修线路或设备可能产生感应电压时,应加装接地线或使用个人保安线。
A. A. 交叉跨越
B.B.接触
C.C.平行
D. D. 邻近
[单选题]允许速度Vmax≤120km/h正线,轨道动态质量容许偏差管理值,水平I级偏差管理值为( )mm。
A.18
B.10
C.8
D.12
[多选题]童某涉嫌故意杀人案,下列证据中属于书证的有()
A.精神病医院为其开具的精神病情况的医疗诊断
B.案发现场找到的童某写的一封尚未邮寄出去的家信,通过对信上的笔迹鉴定,找到了犯罪嫌疑人童某
C.童某家中发现的作案计划
D.被害人临死之前在地上写下的一组数字,通过数字查到了童某的门房号码
[单项选择]“气之本”指的是()。
A. 肝
B. 心
C. 脾
D. 肺
E. 肾