读“黄土高原示意图”,完成下面小题。
1.“造成当地沟壑纵横、支离破碎”的主要原因是( )
①土质疏松②夏季多暴雨③河流结冰④植被稀少
A.①②③ | B.②③④ | C.①②④ | D.①③④ |
A.退耕还林还草 | B.沟谷打坝淤地 | C.塬面平整土地 | D.缓坡修建梯田 |
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