【单选题】【消耗次数：1】
关于恒功率负载，说法正确的是
①
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100306_201.png"/>=常数，<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100946_605.png"/>
②
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100349_854.png"/>=常数，<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205101424_297.png"/>
③
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100429_32.png"/>=常数<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100441_452.png"/>
参考答案：
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相关题目
【单选题】
变压器负载运行时，随着负载电流的增大，其铁心损耗<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100008_669.png"/>和铜损耗<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100015_370.png"/>会（）
①
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205095339_393.png"/>增大，<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205095346_882.png"/>不变
②
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205095355_176.png"/>不变，<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205095359_427.png"/>增大
③
都会增大
【单选题】
单相变压器磁路饱和时，主磁通<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205101139_207.png"/>和励磁电流<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100752_202.png"/>的波形（）
①
同时为正弦波
②
同为尖顶波
③
不会同时为正弦波
【单选题】
甲乙两个车间工人日加工零件数的均值和标准差如下:甲车间:<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191204/20191204133016_901.png"/>=70件,<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191204/20191204133853_863.png"/>=5.6件,乙车间:<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191204/20191204132636_598.png"/>=90件,<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191129/20191129164519_624.png"/>=6.3件,哪个车间日加工零件的离散程度较大()
①
甲车间
②
乙车间
③
两个车间相同
④
无法作比较
【单选题】
额定电压为220/110V的单相变压器，低压边漏电抗为0.075<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205095750_736.png"/>，折合到一次侧为：
①
0.075<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100447_597.png"/>
②
0.15<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205100458_35.png"/>
③
0.3<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205095823_483.png"/>
【单选题】
关于三相异步电动机转子边产生的磁动势<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205101252_49.png"/>的旋转速度说法正确的是（）
①
相对定子边磁动势<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191205/20191205101305_33.png"/>静止
②
相对定子静止
③
相对转子静止
【单选题】
设<imgwidth="69"height="22"v:shapes="_x0000_i1152"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image208.png">是来自正态总体<imgwidth="58"height="22"v:shapes="_x0000_i1153"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image210.png">的样本,已知统计量<imgwidth="118"height="22"v:shapes="_x0000_i1154"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image212.png">是方差<imgwidth="18"height="18"v:shapes="_x0000_i1155"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image214.png">的无偏估计量,则常数<imgwidth="12"height="18"v:shapes="_x0000_i1156"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image216.png">等于（）
①
<imgwidth="12"height="37"v:shapes="_x0000_i1157"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image218.png">
②
<imgwidth="12"height="37"v:shapes="_x0000_i1158"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image220.png">
③
2
④
4
【单选题】
根据等效关系的传递性，若有状态<imgwidth="24"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj056978.png">和<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057002.png">等效，又有状态<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057032.png">和<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057056.png">等效，则状态<imgwidth="24"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057085.png">和<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057109.png">也等效。正确的写法是：______。
①
(<imgwidth="24"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057153.png">,<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057177.png">),(<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057203.png">,<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057227.png">)-à(<imgwidth="50"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057254.png">)
②
(<imgwidth="50"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057281.png">),(<imgwidth="54"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057307.png">)-à(<imgwidth="50"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057334.png">)
③
(<imgwidth="24"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057361.png">,<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057385.png">),(<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057411.png">,<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057435.png">)-à(<imgwidth="24"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057462.png">,<imgwidth="25"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057486.png">)
④
(<imgwidth="50"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057513.png">),(<imgwidth="54"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057539.png">)-à(<imgwidth="54"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/szlj05.files/szlj057566.png">)
【单选题】
设<imgwidth="12"height="14"v:shapes="_x0000_i1185"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image253.png">个随机变量<imgwidth="86"height="22"v:shapes="_x0000_i1186"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image239.png">是独立同分布，<imgwidth="164"height="42"v:shapes="_x0000_i1187"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image255.png"><imgwidth="32"height="20"v:shapes="_x0000_i1188"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image257.png"><imgwidth="115"height="42"v:shapes="_x0000_i1189"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image259.png">，则下列结论中，正确的是（）
①
<imgwidth="12"height="14"v:shapes="_x0000_i1190"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1191"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的无偏估计量
②
<imgwidth="12"height="14"v:shapes="_x0000_i1192"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1193"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的极大似然估计量
③
<imgwidth="12"height="14"v:shapes="_x0000_i1194"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1195"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的极大似然估计量
④
<imgwidth="12"height="14"v:shapes="_x0000_i1196"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1197"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的极大似然估计量
【单选题】
设总体<imgwidth="14"height="14"v:shapes="_x0000_i1273"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image333.png">服从泊松分布：<imgwidth="217"height="40"v:shapes="_x0000_i1274"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image356.png">，其中<imgwidth="32"height="18"v:shapes="_x0000_i1275"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image358.png">为未知参数，<imgwidth="86"height="22"v:shapes="_x0000_i1276"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image336.png">为样本，记<imgwidth="84"height="40"v:shapes="_x0000_i1277"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image360.png">，则下面几种说法错误的是（）
①
<imgwidth="14"height="18"v:shapes="_x0000_i1278"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image362.png">是<imgwidth="12"height="18"v:shapes="_x0000_i1279"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image364.png">的无偏估计
②
<imgwidth="14"height="18"v:shapes="_x0000_i1280"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image362.png">是<imgwidth="12"height="18"v:shapes="_x0000_i1281"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image364.png">的矩估计
③
<imgwidth="14"height="14"v:shapes="_x0000_i1282"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image365.png">是<imgwidth="35"height="20"v:shapes="_x0000_i1283"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image367.png">的矩估计
④
<imgwidth="14"height="20"v:shapes="_x0000_i1284"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image368.png">是<imgwidth="12"height="37"v:shapes="_x0000_i1285"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image370.png">的矩估计
【单选题】
同步发电机直轴电抗<imgsrc="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191121/20191121093404_378.png"alt=""/>三者之间的大小关系为（）。
①
<imgsrc="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191121/20191121095321_129.png"alt=""/>
②
<imgsrc="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191121/20191121095408_167.png"alt=""/>
③
<imgsrc="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191121/20191121095350_584.png"alt=""/>
【单选题】
设总体<imgwidth="14"height="14"v:shapes="_x0000_i1069"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image002.png">服从两点分布：<imgwidth="259"height="20"v:shapes="_x0000_i1070"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image080.png"><imgwidth="75"height="26"v:shapes="_x0000_i1071"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image081.png">为其样本，则样本均值<imgwidth="12"height="18"v:shapes="_x0000_i1072"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image083.png">的期望<imgwidth="49"height="20"v:shapes="_x0000_i1073"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image085.png">（）
①
<imgwidth="12"height="18"v:shapes="_x0000_i1074"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image087.png">
②
<imgwidth="18"height="22"v:shapes="_x0000_i1075"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image089.png">
③
<imgwidth="32"height="22"v:shapes="_x0000_i1076"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image091.png">
④
<imgwidth="20"height="22"v:shapes="_x0000_i1077"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image093.png">
随机题目
【单选题】
人体内维生素D的生理活性形式为?
①
25-(OH)-D3
②
24，25-(OH)2-D3
③
25-(OH)-D2
④
1，25-(OH)2-D3 1，25-(OH)2-D2
【单选题】
下列关于EAR的说法中,不正确的是( )
①
指可满足生命某一阶段和性别人群50%个体的营养需要量
②
可用于制订RNI,评价或计划人群的摄入量
③
RNI=EAR+2SD 或RNI=1.2×EAR
④
个体摄入量经常低于EAR时,一定表明该个体未达到适宜营养状态
⑤
可用某群体某营养素摄入量低于RNI的百分比来评估该群体中摄入不足的发生率
【单选题】
衡量机体维生素A缺乏的早期诊断指标是?
①
血浆维生素A含量下降
②
视觉暗适应功能降低
③
血浆视黄醇结合蛋白含量下降
④
负荷尿试验维生素A含量下降
⑤
以上都不是