1.下列关于长江各河段水文特征的叙述,正确的是( )
A.甲河段水流平缓,航运发达 | B.乙河段水量锐减,水能丰富 |
C.丙河段江阔水深,航运价值高 | D.长江流域支流稀少 |
①修建水库 ②围湖造田 ③疏通河道 ④清除蓄洪区
A.①③ | B.②③ | C.①② | D.②④ |
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