我们在市场上经常看见许多水果,如热带的香蕉、亚热带的柑橘、温带的苹果等,这主要是由于我国( )
A:跨纬度较广
B:跨经度较广
C:面积广大
D:地形复杂
People are starting to use energy from the sun, wind and water because they cost very ________ and will never ________.
下列不属于相对性状的是( )
又知2CH3CHO+O2 →△催化剂 2CH3COOH.请回答下列问题: