历史上的“地主”是指拥有了比较多的农用土地，并把这些土地中的大部分拿去出租，收取地租的人。标志我国地主阶级被彻底消灭的历史事件是 （   ）

面临1929-1933年经济危机，各国选择了不同的道路。回答小题：

     What is color? Why do some of the things around us look red, some green, others blue?
    Colors are really made by deflected (反射) light. We see color because most of the things reflect light. In the same way, if something is green, it reflects most of the green light. If something reflects all light, it is white. If it doesn't reflect any light, it is black.
Some of the light is reflected and some is taken in (吸引) and turned into (变成) heat (热能).The darker the color is, the less light is reflected, the more light is taken in. So dark-colored clothes are warmer in the sun than light-colored clothes.