单选题What is a rotating item?（）A A rotating item is an individual item that is defined with a common item number. An item is designated as rotating because one wants to be able to create individual asset records by using the information (Classification, Spe

请完成下列Java程序：实现2个下拉式菜单，一个包含exit菜单项，另一个包含item1和item2共2个菜单项。要求选择exit菜单项时，退出程序；选择item1菜单项之后，item1项变为不可选而item2可选；选择item2菜单项时，item2变为不可选而item1可选。

注意：请勿改动main()主方法和其他已有语句内容，仅在下划线处填入适当的语句。

程序运行结果如下：

import java.awt.*;

import java.awt.event.*;

public class ex18_2 extends Frame. implements ActionListener {

private choiceHandler ch;

private MenuItem item1;

private MenuItem item2;

public static void main(String[] arg) {

new ex18_2 ( );

}

ex18_2 ( ) {

setTitle("ex18_2");

MenuItem item;

ch = new choiceHandler();

MenuBar mb = new MenuBar();

Menu fm = new Menu("File");

fm.addSeparator();

fm.add(item = new MenuItem("Exit"));

item.addActionListener(this);

fm.add(item);

mb.add(fm);

Menu mm = new Menu("Choice");

mm.add(item1 = new MenuItem("item1"));

item1.addActionListener(ch);

mm.add(item2 = new MenuItem("item2"));

item2.addActionListener(ch);

mb.add(mm);

setMenuBar(mb);

setSize(200,200);

show();

}

public void actionPerformed(ActionEvent ae) {

if(ae.getActionCommand().equals("Exit"))

System.exit(0);

else

System.out.println(ae.getActionCommand());

}

class choiceHandler implements ActionListener {

public void actionPerformed(ActionEvent ae) {

String strCommand = ae.getActionCommand();

if(_________________) {

item2.setEnabled(true);

item1.setEnabled(false);

} else if(______________________) {

item2.setEnabled(false);

item1.setEnabled(true);

}

}

}

}

The core(核心) item in the Oil Record Book Part I is______, and its main content is______.

A.Item A, BALLAST OR CLEANING OF FUEL OIL TANKS

B.Item B, DISCHARGE OF DIRTY BALLAST OR CLEANING WATER FROM FUEL OIL TANKS REFERRED TO UNDER SECTION(A)

C.Item C, DISPOSAL OF OIL RESIDUES(SLUDGE)

D.Item H, BUNKERING OF FUEL OIL

表示窗体集合中的第一个窗体对象的是( )。

A．Forms.Item(0)

B．Item(0)

C．Forms.Item(1)

D．Item(1)

An application needs a table for each connection that tracks the ID and Name of all items previously ordered and committed within the connection. The table also needs to be cleaned up and automatically removed each time a connection is ended. Assuming the ITEMS table was created with the following SQL statement:CREATE TABLE items item_no INT, item_name CHAR(5), item_qty INT)Which of the following SQL statements will provide the table definition that meets the specified requirements?（）

A.DECLARE GLOBAL TEMPORARY TABLE tracker AS (SELECT item_no, item_name FROM items) WITH NO DATA ON COMMIT PRESERVE ROWS ON DISCONNECT DROP TABLE

B.DECLARE GLOBAL TEMPORARY TABLE tracker AS (SELECT item_no, item_name FROM items) WITH NO DATA ON COMMIT PRESERVE ROWS

C.CREATE TABLE systmp.tracker AS (SELECT item_num, item_name FROM items) WITH NO DATA ON COMMIT PRESERVE ROWS

D.CREATE TABLE tracker AS (SELECT item_num, item_name FROM items) ON COMMIT PRESERVE ROWS ON DISCONNECT DROP TABLE

The core item in the Oil Record Book Part I is ____, and its main content is____.

A.Item A, BALLAST OR CLEANING OF FUEL OIL TANKS

B.Item B, DISCHARGE OF DIRTY BALLAST OR CLEANING WATER FROM FUEL OIL TANKS REFERRED TO UNDER SECTION(A)

C.Item C, DISPOSAL OF OIL RESIDUES(SLUDGE)

D.Item H, BUNKERING OF FUEL OIL