柜、屏、台、箱、盘的金属柜及基础型钢必须接地(PE)或接零(PEN)可靠;装有电器的

题型:单项选择题

问题:

柜、屏、台、箱、盘的金属柜及基础型钢必须接地(PE)或接零(PEN)可靠;装有电器的可开启门和框架的接地端子间应用()连接,且有标识。

A、BV多股铜线

B、裸体多股钢线

C、黄绿双色铜芯线

D、裸编织铜线

考点:质量员质量员(安装工程)质量员(安装工程)题库
题型:单项选择题

某同学在做测电池电动势和内阻的实验中,采用了如图甲所示的电路图,保护电阻的阻值为2Ω,请回答下列问题:

小题1:请按照电路图,在图乙中连接实物图。

小题2:该同学正确地连接了电路后,发现闭合电键后,电流表的示数为零,电压表的示数不为零;接下来,该同学用多用电表的电压档检查电路,把两个表笔分别接在时,示数均为零;接在时,示数与电压表示数相同,各个接线柱均未接错,且接触良好,各接线柱之间也并未发生短路,由此可推断故障原因应是       

小题3:排除故障后,该同学顺利完成实验,测得六组实验数据,如下表所示,

1.201.101.000.800.700.60
0.100.140.170.230.270.30
根据数据在坐标图丙上画出图线,并回答该电池的电动势         V,内阻          Ω(均保留两位有效数字)。

题型:单项选择题

A controversial decision on whether choice cuts of steak and cartons of milk produced from cloned animals are suitable for the dinner table is now long overdue.

Hundreds of pigs, cows and other animals created with the help of cloning are living (1) farms across the United States and (2) the forthcoming ruling will directly (3) American consumers, British holidaymakers may also (4) themselves at the forefront of a food revolution that many commentators expect will (5) arrive here.

(6) the birth of Dolly the sheep-the first mammal cloned from an adult cell--there were extreme predictions of herds of genetically (7) bulls and pastures (8) with cloned dairy cows.

That double (9) of the past decade has not yet been realized (10) clones have become a familiar sight at agricultural fairs in America, where producers of (11) pigs and cattle have been among the first to (12) cloning, which offers a way to keep (13) traits without inbreeding problems caused by traditional methods. Clones of rare and elite animals, including sheep, goats, and rabbits, (14) a way to improve animal healthy, (15) the nutritional value of meat and milk, and breed animals immune (16) diseases or better suited for developing countries.

The safety of cloned (17) has been under examination by various bodies. Three years ago the US National Academy of Science concluded that (18) available data indicated that cloning met animal welfare and food safety considerations, more information was needed. (19) scientific evidence suggests that there is little (20) for alarm, at least on food-safety grounds.

19()

A.propose

B.offer

C.exhibit

D.present

题型:单项选择题

依据《中国南方电网有限责任公司电力安全工作规程》,值班负责人是指调度室、厂站、()等24小时全天值班的当值负责人。

A.集控(巡维)中心

B.监控中心

C.配电网值班

D.电话待班

题型:单项选择题

需求分析是企业信息网络规划的基础,而合理的企业信息网络规划目标,是使设备的能力与企业业务要求相匹配的前提。

题型:单项选择题

目前的许多选好解方法,大都以各目标之间()为前提。

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