(2015•枣庄)俗话说“千里之堤溃于蚁穴”,这种现象说明( )
A:环境能影响生物
B:生物能影响环境
C:环境能适应生物
D:生物能适应环境
Chinese athletes did a great job in 2012 London Olympics. It can encourage post-90s(90后) _______.
若am=3,an=5,求a2m+3n和a3m﹣2n的值.