A.关节头和关节窝表面覆盖着一层关节软骨,有利于关节的灵活运动 |
B.小肠绒毛内分布着丰富的毛细血管,有利于肠道内营养物质的消化 |
C.肺泡外有丰富的弹性纤维,有利于呼吸时肺泡与外界的气体交换 |
D.肾小管外有毛细血管网,有利于将原尿中的有用物质重吸收回血液 |
同类型试题
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2