热门试题:
[单选题]已知甲方案投资收益率的期望值为 15%,乙方案投资收益率的期望值为 12%,两个方案都存在投资风险。比较甲、乙两方案风险大小应采用的指标是( )。
A.方差
B.净现值
C.标准离差
D.标准差率
[单项选择]变压器比率制动差动保护中制动分量的主要作用是()
A. 躲励磁涌流
B. 在内部故障时提高保护的可靠性
C. 在外部故障时提高保护的安全性
D. 在内部故障时提高保护的快速性
[单项选择]男,28岁,腹痛呕吐。CT示胰腺弥漫增大,结构不清,胰周有较多渗液,部分包裹,局部可见气泡影,诊断为()
A. 急性水肿性胰腺炎
B. 急性坏死性胰腺炎
C. 急性胰腺炎,假囊肿形成
D. 急性胰腺炎,脓肿形成
E. 急性胰腺炎,伴有出血
[单选题]会议电视的编解码器可以接受PAL,NTSC制式()彩色信号。
A.A、模拟
B.B、数字
C.C、平稳
D.D、实时
[单项选择]Many Americans harbor a grossly distorted and exaggerated view of most of the risks surrounding food. Fergus Clydesdale, head of the department of food science and nutrition at the University of Massachusetts-Amherst, says bluntly that if the dangers from bacterially contaminated chicken were as great as some people believe, "the streets would be littered with people lying here and there."
Though the public increasingly demands no-risk food, there is no such thing. Bruce Ames, chairman of the biochemistry department at the University of California, Berkeley, points out that up to 10% of a plant"s weight is made up of natural pesticides (杀虫剂). Says he: "Since plants do not have jaws or teeth to protect themselves, they employ chemical warfare." And many naturally produced chemicals, though occurring in tiny amounts, prove in laboratory tests to be strong carcinogens—a substance which can cause cancer. Mushrooms (蘑菇) might be banned if they were judged by the same standards that apply to food additives (添加剂). Declares Christina Stark, a nutritionist at Cornell University: "We"ve got fat worse natural chemicals in the food supply than anything man-made."
Yet the issues are not that simple. While Americans have no reason to be terrified to sit down at the dinner table, they have every reason to demand significant improvements in food and water safety. They unconsciously and unwillingly take in too much of too many dangerous chemicals. If food already contains natural carcinogens, it does not make much sense to add dozens of new man-made ones. Though most people will withstand the small amounts of contaminants generally found in food and water, at least a few individuals will probably get cancer one day because of what they eat and drink.
To make good food and water supplies even better, the Government needs to tighten its regulatory standards, stiffen its inspection program and strengthen its enforcement policies. The food industry should modify some long-accepted practices or turn to less hazardous alternatives. Perhaps most important, consumers will have to do a better job of learning how to handle and cook food properly. The problems that need to be tackled exist all along the food-supply chain, from fields to processing plants to kitchens.By saying "they employ chemical warfare" (Line 4, Para. 2), Bruce Ames means "______".
A. plants produce certain chemicals to combat pests and diseases
B. plants absorb useful chemicals to promote their growth
C. farmers use man-made chemicals to dissolve the natural chemicals in plants
D. farmers use chemicals to protect plants against pests and diseases
[多项选择]甲殴打乙致轻微伤,公安局对甲作出拘留15日的处罚裁决。甲不服,经复议后,向人民法院起诉,乙作为第三人参加诉讼。关于本案处理,正确的做法有哪些( )
A. 乙有权对一审判决提起上诉
B. 被告公安局有权提起反诉
C. 人民法院有权判决被告公安局对乙予以处罚
D. 人民法院有权变更公安局对甲的处罚
[判断题]16V240ZJB柴油机的控制机构由调节杠杆、紧急停车拉杆系统及最大供油止挡组成。
[单选题]安全注意事项,架车机应平稳()放置,并确认升降方向一致。
A.横向
B.垂直
C.纵向
[单选题] 简易式、( )3种是按脱粒机完成脱粒作业和结构复杂程度分类的。
A.半复式和复式
B.牵引式和自走式
C.半喂入式和全喂入式
D.叶轮式和轴流式
[简答题]指挥机车向显示人方向稍行移动的信号昼间、夜间手信号及音响信号如何显示?
[判断题] 破拆门窗玻璃时,必须站在门窗侧面,从玻璃下方一角开始破拆。()
A.正确
B.错误
[单选题]二类变电站由( )组织编制变电站生产准备工作方案,报省公司运检部审核批准。
A.运检部
B.运维室
C.检修室
D.运维单位
[单选题]诚信税务师事务所于2019年成立,2019年的纳税信用得分为80分。则诚信公司2020年度信用评价中“上一评价周期信用情况”的得分应为:( )
A.70分
B.80分
C.14分
D.16分
[单选题]在国际单位制中,电压的单位( )。
A.A
B.Ω
C.V
D.W
[单项选择]侵蚀性葡萄胎与绒毛膜癌最根本的区别为()。
A. 滋养细胞增生的程度
B. 距葡萄胎排出后的时间长短
C. 葡萄胎排净后尿内HCG值的高低
D. 子宫增大的程度
E. 病理检查有无绒毛结构
[单项选择]
W: You have a telephone call, Mr. Smith.
M: Who is it
W: He didn’t say.
M: Tell him I’m not in the office. Say I’ll be back by four o’clock.
W: All right. Hello, sir...
M: Yes
W: I’m afraid he’s just stepped out of the office. May I ask who’s calling
M: Yes, this is Edgar Davis from Boston.
W: Oh, yes, Mr. Davis. I am afraid he won’t be back until four o’clock. Could you give me your number, please.
M: Yes.
Where does Edgar Davis call from( ).
A. British.
B. Brazil.
C. Boston.
[单选题] 配电变压器柜的( )应有防误入带电间隔的措施,新设备应安装防误入带电间隔闭锁装置。 (1.0分)
A. 柜体
B. 后盖
C. 柜门
D. 操作把手
[判断题]DCS的结构是一个集中式系统。
A.正确
B.错误
[多选题]下列防爆电气设备适用于1区危险环境的有( )。
A.隔爆型(d)
A.粉尘防爆型
B.本质安全型(ib)
C.本质安全型(i
D.
E.油浸型(o)
[单项选择]可摘局部义齿恢复功能、避免组织损伤的基础是义齿的
A. 坚固耐用
B. 摘戴方便
C. 外形美观
D. 固位和稳定
E. 保健作用
[判断题]作业负责人、驻站联络员、现场防护员,必须携带列车无线调度电话等通信设备。
A.正确
B.错误
[多选题]新时代大学生要树立大历史观和正确党史观,准确把握党的历史发展的主题主线、主流本质……真正 ( )
A. 理解历史
B. 把握历史
C. 增强历史自觉
D. 增强历史自信
[判断题]CRH2A(头型)动车组,双日检按 5 名检修人员为 1 组,40 分钟检查完成 1 编组(8 辆时)为目标进行检修工作。
A.正确
B.错误
[单项选择]对复费率电能表,进行走字试验时,连续走字时间大于72h,小负载电流运行的时间不得少于总时间的20%,且期间要有()的断电送电过程,以检查单片机运行是否正常,数据保存是否正确。
A. 三次以上
B. 两次
C. 两次以上
D. 三次
[单选题]充装爆炸性气体混合物的容器管径越小,爆炸极限( )。
A.上下限之间范围越大
B.上下限之间范围越小
C.上限越高
D.下限越低
[多选题]放线牵引板经过跨越档两侧铁塔和跨越架时,跨越场应协同牵引场和张力场,调整放线( ),使其顺利通过放线滑车,并听从跨越场的指挥。(DL/T 5106—2017《跨越电力线路架线施工规程》5.5.5)
A.牵引速度
B.牵引角度
C.牵引张力
D.牵引板姿态
[判断题]单人操作时若需进行登高或登杆操作,应做好相应的安全措施。
A.正确
B.错误
[判断题]乘务科和各车队应指定专人负责失信行为信息和相关证据的审核、保管、管理等工作,加强铁路客运管理信息系统失信管理账户和密码的管理。
A.正确
B.错误
[单选题]钢丝绳在起升机构的滑轮与卷筒多次弯曲造成的弯曲疲劳是钢丝绳破坏的主要原因之一。
A.正确
B.错误
[单项选择]在项目投资机会研究中对投资估算精度的要求一般应达到( )。
A. ±10%
B. ±15%
C. ±20%
D. ±30%
[多选题]目标距离-速度控制模式根据 及列车本身的性能,确定列车制动曲线,采取连续式一次制动模式控制列车运行。
A.目标距离
B.目标速度
C.运行速度
D.线路长度
[单选题]阵发性室上性心动过速的心室率一般为()
A.150-250次/分
B.260-300次/分
C.100-120次/分
D.350-600次/分
E.>600次/分
[简答题]MR有载分接开关定期检修包括哪些工作内容?应注意哪些问题?
[单选题]机械车联挂运行时,由第一位担当本务机。驾驶员应认真执行有关()规定,做到“彻底瞭望,确认信号、高声呼唤、手比眼看”,确保各机械车操作同步,谨慎驾驶不超速;遇有降雾、暴风雨雪,扬沙等恶劣天气时,应降低速度运行
A.行车
B.安全
C.技术
D.设计
[单项选择]以下关于申请实施绿色通道制度的企业应具备条件的表述,错误的是______。
A. 信誉良好,诚信度高
B. 年出口额500万美元以上
C. 已实施IS09000质量管理体系
D. 半年内无违规报检行为