【单选题】
有以下程序段int?a[10]={1,2,3,4,5,6,7,8,9,10},*p=&a[3],b;b=p[5];b中的值是()
【单选题】
若有以下数组说明inta[12]={1,4,7,10,2,5,8,11,3,6,9,12};则i=10;a[a[i]]元素数值是( )。
【单选题】
若有定义:inta[10]={0,1,2,3,4,5,6,7,8,9},*p=a;,则()表达式是错误的。
【单选题】
若有以下说明,int?a[12]={1,2,3,4,5,6,7,8,9,10,11,12};?则数值为4的表达式是()
【单选题】
已知int a[10]={0,1,2,3,4,5,6,7,8,9},*p=a;不能表示数组a中元素的式子是()
【单选题】
向量空间<imgwidth="216"height="28"src="data:image/png;base64,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"/>的维数等于()
【单选题】
已知:inta[][3]={1,2,3,4,5,6,7,8,9,0};则数组a的第一维的大小是()
【单选题】
设A={1,2,3,4,5},B={6,7,8,9,10},以下关系是从A到B的入射函数的是( )
【单选题】
设两个变量X与Y,其中误差分别为<img class="kfformula" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAQ4AAAAtCAYAAABf/oWJAAAKg0lEQVR4Xu2cZaw0SxGGn4s7XDS4u2sI7pLg7haCE9xDsGAXd7eLu3twC+5O0OAOwTVPUpV0JnvO2Z7dMztnv+pfX77tmemu6n77rbeqz2FUKwuUBcoCnRY4rLN/dS8LlAXKAhRw1CIoC5QFui1QwNFtsnqgLFAWKOCoNVAWKAt0W6CAo9tk9UBZoCxQwFFroCxQFui2QAFHt8nqgbJAWaCAo9ZAWaAs0G2BAo5uk9UDZYGyQAFHrYGyQFmg2wIFHN0m26oH9P/DgGsANwH+CLwK+DlwV+DPWzXb7ZrMRn1XwLFdi6l3NscHnhUPCRSnBl4HvBp4bO/Lqv+kFtio7wo4pvG1dj438GvglyM+eQbg9sB/gb8D5wW+DLwo3jl8pb/fCPgCcLzo/wzgJ4OOpwJeCXwEeARw6fj3tYG3jRjntj5yCuBkwNeB/3VO0uduBxwNOCdwbOD5wAeAfw/e5Tq5DHAF4NPAGYETAc8Bfjcn3xVwdK6Ckd1dLE8BPhYbtec1FwauCLjx/xYP+r5HAxcEbgP8qHnhZYE7A/doQMoFK4N4EPDNpu/5gDcA9w2guFX8W9D5Vs8gt7zvzQNU79X4YJkpnzb8I6tz47vfLhEsT1b3pAY8/O2m8fsDgL/EBxb505826rsCjmXcv3qfscBxDOAxgMzAxdQyBk8mmcK9A5Qc5eHA84DXAG9qhq2fXfS+5yHAP+K3awFPBG4AfDX0josAtwR+v/q0t+YNY4DjqMB9gLcC3x74QvYoaGhnf7fJKl8IPBj4TNP/mMARwPeBpzeMZ6O+K+CYZm2PBQ4Xnxv9esDNgG80w70k8PFYaKlHXCxosMzhK4OpXRl4AnDjZiELJrIZF7Bg8rQIfR4K/Gca0xyIr4wBjtOHXd30/xzM8uzAa4EPAg+M3/Xx3QG/9bNB/zsC14n3/SZ+26jvCjimWbdjgWO30QkOzwSuG/GyfV1g/r8g04Yv/mbI83bg1sD7p5n21nxlDHBcHHhf6FCyiAwzNcpJmpDVd/8BeBRw1tCyzG61rWUXwwNhI0aeEjj81vVDIBKNTftJtS8HeFJ+L0QhadrLg3Yb8xnrufEUF6XtQ4FvI4br/Oi6geO4ARpHiVPqTzEemYJMxMX42x1OOVmHgmhvU9y7E3Ac4CzAs0Mv8SQ8JfAL4KqhmbwL0Mf67wfA2UIcfOoCka93HJvoPwY4tNFLgc8GK2yBQ8HU9S9gGLbISNTAbIt0lGSXlwI+sQkDDL85JXCoEHvaSavvD0idVf1V7z8UsZtx+zsi1j5pxIGKSpl6kqYltZuD/ZYdwzqBQ7CQUcg01DeSWeQ3jJV3Aw4p8phUq+DuKWomx/jcTMNPgecCXwtDyHb0jzqLsXkKupm90de5QZa13Rz6jQGO3cadwqZalNksMyeC+Q/3AA5rbfTfxtuUwKHxfxUs43GBtJ5gqsuZ4ko6LaCIxJ5itr02RY8hrwTcr+eBpu974qT/V+fz6wAOQdU0qxtYsHBTmt7NtpeNMq5+Y9Dinim4ThT6pN5+WxHvonEQyBqzSakV+14QGyAzA0nNd9oYy47lPJFNOtayDzT9TF+7SXNMPa9YJ3CkUO36FggMPfayTzKOW4xkiz1zXarvVMBx9EjzSc+k1YYi0jSLjtp4LheeIU2bFTBb4DNWNJpm/OtSs5u2kxv63cCJR37WDXfbJbMZFmqZDTGs88SXBu8ncJwg/CfTkGZ7UlqHoHDb1iJIswVlw5c2MyBt9xnZpJu3txZipEmXfsz19RLA+pUxTVZ89cGcd3qPbOMVgIdnHpoFHEtYPWmaRS0tbRXEXIjWEAzrCM4RFY069yBS3XUwjqFptaOb8WUROgjO2mavUGUM42i/bYgp8xgWieUczxyhVMuGMnV8UAvL1sU4DO9c9+8MvyXoFnAsARymA13wVxmo+6ljuAClcUMmIkqL6rMQh5aYZ9tlP4DjhBEyqMRninU/xdGcj0VkMiNrP1qFP3WMLy7QoWQi6lttKrjThBvtvg7gUNB+PKB9BPuWqeX6cJIlji5wtXUJpp0EDeM7MynZks56mrV1BBZBSeusfrTeIPPYG11JnR8fCxzGtgqNL44ai7a2It9pCjbVdv9t1eiiDZpx8hCwe6aS4G44NiwSy/SjoYpjzpYAZ5ant/KyZ2z72XdV4FAoNsT+cYibw1At98WFdhC2/b6XEYdgvZ9z3vXdU2kcw0VkTD68fbkTBc7UrfqBZdZScbMKFtb0ipSO4yCJo6n5mIV68qAoKzexIUsCheCgOq9G9PmB533XI1c89ds0+rBITNBycV9z8O0UvAUUx6YW5AZRm+ltB1EcNY1tYZei8psH+s7lgS+FriU43GWHGhwBV8CfzcE5NXCkvnFkgECLvDtR4AQUa/Y/GmlIBVbFOZtinaesYuuZImtjnO09ATMPLavpXajr6j+WcZjCdkFZe5Fl4jkm61peD1gzkWXkWXL+3kibZt880WRvbcl57/zSF0N13yyHwum5FlQ+CigeEupWll7rKzMxXhgzDXkHQPHV0DTBUeAzg2TaeDjv3jGvo/9YxuH+kiX45wn0SbverYfRNmao/N0D0boPGXmubceeB4QHQVtyvo55jX7H1MCRJ+hQJNuNArcnpYvLWNmKSdNqUkDThAp+3jqV0hvKmOv2YtE9AVOom25jgUP/3DCuu3ujMlOJxssyLsO7uwHfbSYowPp/nnKZzjbME3w89dtLbr12yazJkFWkvmFJvP7wBm82n7EwzM138ihxl20Y43uCOp7zB1NRO/H/9Z3A4hznkIEZAxx5aU2AX1SpK3vzYBAoDEGzv0KyNkxfe1PWsgX9OeZmda+Pl+o/NXBoAFN1Im1bEu1J6aYXaV007WLxVJICWzEqUIjQqdi7EC8QjjldUGFBRfF16paU3CrKMc30s9evh+XG+siskjTWBaZWIHPz1DZFvai/t2YN5z4ZJ5b9ZV/WUYxtZm1MpTo/C8/aS3AyPDNegpNl7W07TTynKOg7EgBlP4KcYOPYnI8navpRn7cn79hxL/OcOozrz/siY5plAkMwdV2+JSpod3qnh6DsO5vFfQKFQPvhABb3hkDbZqnGjHGtz0wNHGsd/OBleYlreBlsP79Z717dAmoeblr/PMDnoqLYcMoqVMXEajO0wLYAR9aAePJJ06W7Iren2ByLxWa4FDY2JNmnIqFah7G+oJF+HFPlubGJHEofPujAkalHF9vD40KRar9/yUp6b1pwDjHyobSmeueqKG44Y1yvFuRdGK+bG3JWm6kFDjpwKCRdLeK/74SC7Z9cU2z19madWDNdeM2wLGAzTWy6XZ1IMdisyqfmP/RDd4QHHTgOXc9t58zVqRRe1Ttmk0HYTlOvNqsCjtXsV0+vZgG1DbNkeTfJi3vqUqbTK8Rczbb7+nQBx76at16+hwUs8rKWQ03DsnlTkP7bv+ZebcYWKOCYsXNqaGWBuVqggGOunqlxlQVmbIECjhk7p4ZWFpirBQo45uqZGldZYMYWKOCYsXNqaGWBuVqggGOunqlxlQVmbIECjhk7p4ZWFpirBQo45uqZGldZYMYWKOCYsXNqaGWBuVrg/9NDcUxOGzKJAAAAAElFTkSuQmCC" data-latex="{m}_{x}=\pm 30″{m}_{y}=\pm 20″"/> 、,则X+Y的中误差为<img class="kfformula" src="data:image/png;base64,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" data-latex="\pm 36″"/>,X-Y的中误差为<img class="kfformula" src="data:image/png;base64,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" data-latex="\pm 22″"/>
③
C.企业与专职专业人员签订劳动合同,且专职专业人员符合国家规定的职业年龄
④
D.专职专业人员人事档案关系由国家认可的人事代理机构代为管理
【单选题】
在建筑工程中,一般以()为假定水准面,设其高程为<img class="kfformula" src="data:image/png;base64,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" data-latex="\pm 0.000m"/>
【单选题】
设A={{1,2,3},{4,5},{6,7,8}},下列选项正确的是( )