72.超声波在单一介质中的传播方向是
<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 72.超声波在单一介质中的传播方向是<br><br><img src=""><br>A.四周球面传播<br>B.曲线传播<br>C.直线传播<br>D.发散角很小的近乎直线传播<br>E.双向传播<br><br>正确答案:A<br><div id="parserbtn"><input class="parserbtn"onclick="viewparser(1,11378);" type="button" name="parserbtn" value="查看解析" style="height: 23px"></div><br>
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