How many ____ (people) does your family have?
7×0.7=____
7×0.7×0.7=____
7×0.7×0.7×0.7=____
7×0.7×0.7×0.7×0.7=____
7×0.7×0.7×0.7×0.7×0.7…____
解方程:
下图是NaCl、MgSO4的溶解度曲线。下列说法正确的是( )
切洋葱时常会引起流泪,原因是洋葱细胞中含有对眼睛有刺激的物质,这些物质主要存在于( )