29.超声波频率由以下哪项决定
<script>function viewparser(etype,eid){showWindow("showMsgBox", "plugin.php?id=tpgao_questionsyn:showMsg&timutype="+etype+"&item="+eid+"&credit=3&mod=sh", "get", 0);
}</script>[普通选择题]<br> 题目 29.超声波频率由以下哪项决定<br><br><br>A.晶体所处的交变电场的频率<br>B.晶体所处的介质的密度<br>C.晶体的长度<br>D.晶体的宽度<br>E.晶体的体积<br><br>正确答案:A<br><div id="parserbtn"><input class="parserbtn"onclick="viewparser(1,13662);" type="button" name="parserbtn" value="查看解析" style="height: 23px"></div><br>来自《B18Z专业知识(291题)》试卷<br><br>
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