请问怎么把下拉表放到第一行的后面？

 import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class num1 extends JFrame{
    Box b1,b2,b3,b4,b5,b6,b;
    JTextField t1,t2,t3,t4,t5,t6;
    num1(){
        b = Box.createVerticalBox();
        
        JPanel pane = new JPanel();
        pane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(pane);
        JLabel abe = new JLabel("@");
        pane.add(abe);
        JComboBox q1 = new JComboBox();
        q1.addItem(");
        q1.addItem(");
        q1.addItem(");
        pane.add(q1);
        this.setLayout(new  GridLayout(1, 1));
        pane.setBounds(100, 10, 400, 40);
        
        t1 = new JTextField();
        t1.setPreferredSize(new Dimension(100,10));
        b1 = Box.createHorizontalBox();
        b1.add(new JLabel("*邮件地址"));
        b1.add(Box.createHorizontalStrut(10));
        b1.add(t1);
        
        
        
        t2 = new JTextField();
        t2.setPreferredSize(new Dimension(100,10));
        b2 = Box.createHorizontalBox();
        b2.add(new JLabel("*密码"));
        b2.add(Box.createHorizontalStrut(10));
        b2.add(t2);
        
        
        t3 = new JTextField();
        t3.setPreferredSize(new Dimension(200,10));
        b3 = Box.createHorizontalBox();
        b3.add(new JLabel("*确认密码"));
        b3.add(Box.createHorizontalStrut(10));
        b3.add(t3);
        
        t4 = new JTextField();
        t4.setPreferredSize(new Dimension(150,10));
        b4 = Box.createHorizontalBox();
        b4.add(new JLabel("手机号码"));
        b4.add(Box.createHorizontalStrut(10));
        b4.add(t4);
        
        t5 = new JTextField();
        t5.setPreferredSize(new Dimension(100,10));
        b5 = Box.createHorizontalBox();
        b5.add(new JLabel("验证码"));
        b5.add(Box.createHorizontalStrut(10));
        b5.add(t5);
        
        t6 = new JTextField();
        t6.setPreferredSize(new Dimension(140,10));
        b6 = Box.createHorizontalBox();
        b6.add(new JLabel("短信验证码"));
        b6.add(Box.createHorizontalStrut(10));
        b6.add(t6);
        
        setLayout(new FlowLayout(1));
        b.add(b1);
        b.add(Box.createVerticalStrut(10));
        b.add(b2);
        b.add(Box.createVerticalStrut(10));
        b.add(b3);
        b.add(Box.createVerticalStrut(10));
        b.add(b4);
        b.add(Box.createVerticalStrut(10));
        b.add(b5);
        b.add(Box.createVerticalStrut(10));
        b.add(b6);
        
        add(b);
        
        setLayout(new FlowLayout(0));
        setBounds(200, 200, 800, 800);
        setVisible(true);
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        validate();
    }
}