关于幸福，你只有在失去它的时候才知道你曾经拥有过。

The end of history will be a very sad time. The struggle for recognition, the willingness to risk one's life for a purely abstract goal, the worldwide ideological struggle that called forth daring, courage, imagination, and idealism, will be replaced by economic calculation, the endless solving of technical problems, environmental concerns, and the satisfaction of sophisticated consumer demands.

To signal an emergency， use the rule of three； 3 shouts， 3 horn blasts， or 3 whistles.