A:正方形
B:矩形
C:平行四边形
D:直角三角形
Being happy is a skill that can be learned like a foreign language, and one way to ______ ourselves to be happy is to write down the little things that cheer us up each day.
对于下列四幅图的描述,说法正确的是( )
某固体混合物内含有A、B、C三种物质各10g,将其充分反应后,B消耗完全,C的质量增加了8g,生成了4gD,则参加化学反应的A和B的质量比是( )