【单选题】某220kV变电所,总占地面积为12000m2(其中接地网的面积为10000m2),220kV系统为有效接地系统,土壤电阻率为100Ω?m,接地短路电流为10kA,接地故障电流持续时间为2s,工程中采用钢接地线作为全所主接地网及电气设备的接地(钢材的热稳定系数取70)。试根据上述条件计算下列各题。220kV系统发生单相接地时,其接地装置的接触电位差和跨步电位差不应超过下列哪组数据()?
【单选题】下列堆砌石假山的工程量清单计算规则正确的是( )
【单选题】The lecture mainly deals with the trouble young children have _______ right from wrong.
【单选题】Here is a behavioral question: "Describe a time when you had a deadline and were running out of time. What did you do?" Choose the best way to start your answer.
A.
I had a deadline, so I worked hard.
B.
First, I will assess the situation and decide if I will be able to get the assignment finished on time. Then…
C.
This will never happen to me because…
D.
When I was at university, I had an essay due, and I was worried I wouldn’t finish it in time. Here’s what I did. I realized I needed to assess the situation. First, I created a realistic timetable…
【多选题】下面关于总承包服务费的说法,正确的有
A.
总承包服务费属于建筑安装工程费用中的其他项目费
B.
总承包服务费属于建筑安装工程费用中的企业管理费
E.
由施工单位根据总包服务范围和有关计价规定编制总承包服务费
【单选题】用伏安法测量某一阻值略小于200Ω的电阻,要求测量结果的不确定度最小,应选择下列哪组仪器(不计内阻影响和功率限制):
A.
电流表0.1级、量程10mA,电压表1.0级,量程2V
B.
电流表0.5级、量程50mA,电压表0.5级,量程2V
C.
电流表1.5级、量程10mA,电压表1.5级,量程2V
D.
电流表1.5级、量程15mA,电压表1.5级,量程2V
【单选题】十九大报告中指出:中国共产党人的初心和使命 是( )