A:森林里树枝间的光柱
B:激光测距仪
C:木工检查木料是否平直
D:排队看齐
已知函数f(x)对定义域R内的任意x都有f(x)=f(4-x),且当x≠2时其导函数f'(x)满足xf'(x)>2f'(x)若a<a<4则( )
We went to earth.