问题
选择题
下列有关仪器刻度位置的叙述正确的是
A．容量瓶的体积标线刻在瓶颈上
B．量筒的"0"标线在中间
C．量筒最下端刻有"0"标线
D．托盘天平刻度尺有"0"标线，刻在尺的中间
答案
答案：A
题目分析：量筒无“0”刻度，B、C错误；托盘天平“0”刻度在标尺左端，D错误。
点评：量筒无“0”刻度且从下往上刻度增大。
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下列有关仪器刻度位置的叙述正确的是
A．容量瓶的体积标线刻在瓶颈上
B．量筒的"0"标线在中间
C．量筒最下端刻有"0"标线
D．托盘天平刻度尺有"0"标线，刻在尺的中间
答案：A
题目分析：量筒无“0”刻度，B、C错误；托盘天平“0”刻度在标尺左端，D错误。
点评：量筒无“0”刻度且从下往上刻度增大。
import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.tree.DefaultMutableTreeNode; public class ex23_2 extends JPanel{ static JFrame jfrm; public ex23_2(){ setLayout(new BorderLayout()); DefaultMutableTreeNode root = addNode(); JTree jt = new JTree(root); jt.setRootVisible(true); JScrollPane jsp = new JScrollPane(); jsp.setViewportView(jt); add(jsp); } public DefaultMutableTreeNode addNode(){ DefaultMutableTreeNode root = new DefaultMutableTreeNode("计算机二级"); DefaultMutableTreeNode sub1 =new DefaultMutableTreeNode("java"); DefaultMutableTreeNode sub2 = new DefaultMutableTreeNode("c++"); root.add(sub2); root.add(sub1); DefaultMutableTreeNode magazines = new DefaultMutableTreeNode("参考书"); sub1.add(new DefaultMutableTreeNode ("简介")); sub1.add(new DefaultMutableTreeNode ("大纲")); __________________; magazines.add(new DefaultMutableTreeNode ("指导书")); magazines.add(new DefaultMutableTreeNode ("上机习题集")); __________________.add(new DefaultMutableTreeNode("简介")); return root; } public static void main(String args[]){ jfrm = new JFrame("ex23_2"); ex23_2 obj23_2 = new ex23_2(); jfrm.getContentPane().add("Center",obj23_2); jfrm.setSize(400,250); jfrm.addWindowListener(new WindowAdapter() {public void windowClosing(WindowEvent e) { System.exit(0);} }); jfrm.setVisible(true); } }