On Tuesday August 11th, 1911, a young artist, Louis Beraud, arrived at the Louvre in Paris to complete a painting of the Salon Carre. This was the room where the world’s most famous painting, the Mona Lisa by Leonardo da Vinci, was on display. To his surprise there was an empty space where the painting should have been. At 11 o’clock the museurn authorities realized that the painting had been stolen. The next day headlines all over the world announced the theft.
Actually the Leonardo had been gone for more than twenty-four hours before anyone noticed it was missing. The museum was always closed on Mondays for maintenance. Just before closing time on Sunday three men had entered the museum, where they had hidden themselves in a storeroom. The actual theft was quick and simple. Early the next morning Perrugia removed the painting from the wall while the others kept watch. Then they went out a hack exit.
Nothing was seen or heard of the painting for two y
A. the original painting is still on display at the Louvre
B. the original painting is now in the United States
C. the original painting has been destroyed
D. no one could possibly tell which is the original painting
在面向对象分析与设计中， (38) 是应用领域中的核心类，一般用于保存系统中的信息以及提供针对这些信息的相关处理行为； (39) 是系统内对象和系统外参与者的联系媒介； (40) 主要是协调上述两种类对象之间的交互。
（40）处填（）。我来回答:
