A:呼吸作用
B:呼吸运动
C:气体扩散
D:肺泡的扩张与回缩
关于生物分类单位的叙述错误的是( )
函数f(x)=ax+4的图象恒过定点P,则P点坐标是____.
圆柱的体积是100,圆柱的底面积S与高h的关系式是 ____ .
—They set off from different directions, so they had to go there .