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There are all kinds of trains in the world. There are fast trains and slow trains. Bullet trains are very fast. They can move at the speed of 300 km an hour.
Some trains go under the ground and some trains go through mountains. Can a train run over water? Yes, it can. There are many bridges over the river. The trains can easily run over the water. But it is not easy to build bridges.
In big cities, the streets are usually very busy. So you can find trains under the ground and trains on a rail above the streets. They carry people in and out of the city.
1．There are all kinds of trains in the world.2．A train can't run over water because it's too fast.
3．You can find trains carrying people in and out of big cities.
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
