【单选题】【消耗次数：1】
为了减轻活塞环的磨损， 通常对（ ） 进行镀铬
①
第一道气环
②
第二道气环
③
油环
④
气环和油环
参考答案：
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相关题目
【单选题】
下列活塞环由于截面形状对称， 安装时不需区分上下方向的种类是
①
扭曲环、 梯形环和桶面环
②
矩形环、 锥形环和桶面环
③
矩形环、 梯形环和桶面环
④
扭曲环、 锥形环和桶面环
【单选题】
大脑动脉环（Willis环）的构成
①
两侧大脑前动脉起始段、两侧颈内动脉末端、两侧大脑后动脉、前、后交通动脉
②
两侧大脑前动脉起始段、两侧大脑中动脉、两侧大脑后动脉、前、后交通动脉
③
两侧大脑中动脉、两侧颈内动脉末端、两侧大脑后动脉、前、后交通动脉
④
两侧大脑前动脉起始段、两侧颈内动脉末端、两侧椎动脉、前、后交通动脉
⑤
两侧大脑前动脉起始段、两侧颈内动脉末端、基底动脉动脉、前、后交通动脉
随机题目
【单选题】
设随机变量<imgwidth="100"height="25"v:shapes="_x0000_i1119"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image157.png">独立同分布，且<imgwidth="223"height="41"v:shapes="_x0000_i1120"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image159.png">，则<imgwidth="115"height="46"v:shapes="_x0000_i1121"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image161.png">（）
①
<imgwidth="37"height="21"v:shapes="_x0000_i1122"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image163.png">
②
<imgwidth="36"height="21"v:shapes="_x0000_i1123"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image165.png">
③
<imgwidth="16"height="41"v:shapes="_x0000_i1124"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image130.png">
④
1
【单选题】
下列二阶方阵中可对角化的是（）
①
<imgwidth="68"height="58"v:shapes="_x0000_i1241"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image307.png">
②
<imgwidth="66"height="58"v:shapes="_x0000_i1242"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image309.png">
③
<imgwidth="58"height="58"v:shapes="_x0000_i1243"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image311.png">
④
<imgwidth="68"height="58"v:shapes="_x0000_i1244"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image313.png">
【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">
【单选题】
随机变量X在下面区间上取值，使函数<imgwidth="80"height="21"v:shapes="_x0000_i1167"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image234.png">成为它的概率密度的是（）
①
<imgwidth="46"height="46"v:shapes="_x0000_i1168"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image236.png">
②
<imgwidth="49"height="46"v:shapes="_x0000_i1169"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image238.png">
③
<imgwidth="39"height="27"v:shapes="_x0000_i1170"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image240.png">
④
<imgwidth="70"height="46"v:shapes="_x0000_i1171"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image242.png">
【单选题】
若方阵<imgwidth="100"height="58"v:shapes="_x0000_i1264"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image337.png">，则<imgwidth="18"height="18"v:shapes="_x0000_i1265"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image285.png">的特征方程为（
①
<imgwidth="100"height="58"v:shapes="_x0000_i1266"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image339.png">
②
<imgwidth="112"height="24"v:shapes="_x0000_i1267"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image341.png">
③
<imgwidth="100"height="58"v:shapes="_x0000_i1268"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image343.png">
④
<imgwidth="112"height="24"v:shapes="_x0000_i1269"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image345.png">
【单选题】
下列说法错误的是（）
①
<imgwidth="18"height="18"v:shapes="_x0000_i1311"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image008.png">正交则<imgwidth="22"height="22"v:shapes="_x0000_i1312"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image400.png">正交
②
<imgwidth="36"height="22"v:shapes="_x0000_i1313"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image402.png">正交则<imgwidth="30"height="18"v:shapes="_x0000_i1314"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image404.png">也正交
③
<imgwidth="18"height="18"v:shapes="_x0000_i1315"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image008.png">正交则<imgwidth="62"height="22"v:shapes="_x0000_i1316"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image406.png">
④
<imgwidth="18"height="18"v:shapes="_x0000_i1317"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image008.png">正交则<imgwidth="58"height="28"v:shapes="_x0000_i1318"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds04.files/image408.png">
【单选题】
<imgwidth="476"height="64"v:shapes="图片_x0020_14"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds02.files/image014.png">
①
<imgwidth="65"height="34"v:shapes="图片_x0020_15"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds02.files/image015.png">
②
<imgwidth="67"height="27"v:shapes="图片_x0020_16"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds02.files/image016.png">
③
<imgwidth="112"height="28"v:shapes="图片_x0020_17"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds02.files/image017.png">
④
<imgwidth="110"height="33"v:shapes="图片_x0020_18"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds02.files/image018.png">
【单选题】
<imgwidth="165"height="32"v:shapes="图片_x0020_47"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds01.files/image045.png">
①
<imgwidth="117"height="32"v:shapes="图片_x0020_48"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds01.files/image046.png">
②
<imgwidth="110"height="37"v:shapes="图片_x0020_49"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds01.files/image047.png">
③
<imgwidth="116"height="33"v:shapes="图片_x0020_50"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds01.files/image048.png">
④
<imgwidth="118"height="37"v:shapes="图片_x0020_51"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds01.files/image049.png">
【单选题】
已知<imgwidth="66"height="84"v:shapes="_x0000_i1256"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image318.png">和<imgwidth="80"height="84"v:shapes="_x0000_i1257"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image320.png">是线性方程组<imgwidth="54"height="20"v:shapes="_x0000_i1258"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image297.png">的两个解，则系数矩阵<imgwidth="18"height="18"v:shapes="_x0000_i1259"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image260.png">是（）
①
<imgwidth="102"height="84"v:shapes="_x0000_i1260"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image323.png">
②
<imgwidth="96"height="58"v:shapes="_x0000_i1261"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image325.png">
③
<imgwidth="96"height="58"v:shapes="_x0000_i1262"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image327.png">
④
<imgwidth="106"height="84"v:shapes="_x0000_i1263"src="http://wljy.whut.edu.cn/uploadfiles/word/xxds03.files/image329.png">
【单选题】
设<imgwidth="90"height="25"v:shapes="_x0000_i1095"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image084.png">，则<imgwidth="73"height="44"v:shapes="_x0000_i1096"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image112.png">~（）
①
<imgwidth="64"height="25"v:shapes="_x0000_i1097"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image113.png">
②
<imgwidth="48"height="21"v:shapes="_x0000_i1098"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image114.png">
③
<imgwidth="80"height="41"v:shapes="_x0000_i1099"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image116.png">
④
<imgwidth="108"height="25"v:shapes="_x0000_i1100"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image117.png">