读“珠江三角洲示意图”,完成下面小题。

1.图中甲铁路干线是( )
A.陇海线 | B.京九线 | C.南昆线 | D.京广线 |
A.① | B.② | C.③ | D.④ |
①海陆交通便利 ②水热充足,农业基础好
③煤、铁资源丰富 ④毗邻港澳,邻近东南亚
A.①② | B.②③ | C.①④ | D.③④ |

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

