听到考试的铃声，同学们立刻开始答卷．这个场景说明（　　）

    Do you know what the White House is? Perhaps some of you do，while others don't.

    The White House is a house in Washington. The president of the U.S.A. lives in it. It's really white. But do you know why the White House is white? The story happened in 1812. That year England was at war with America. The British army got to Washington and set the president's house on fire. In 1814，in order to hide the marks of the fire，the stone walls of the president's house were painted white and it has been the “White House” ever since.

进入青春期后，为了克服自己心理、生理上的障碍，最佳的做法是（　　）

观察下列三幅图，可得出的结论是     ____               。