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Water is very important to human beings. We cannot live without clean water, and neither can animals and plants. The water on the Earth was clean in the past, But now many rivers and lakes are polluted, and polluted water is harmful to all living things.
So what shall we do? We can do something.
Firstly, we must stop factories from pouring waste water into rivers.
Secondly, we should stop throwing rubbish into rivers. Many kinds of rubbish may pollute the environment.
Finally, we can tell people how important the water is.
By doing these things, I think water will become cleaner sooner or later.
1．All living things cannot live without clean water.2．Now all the rivers and lakes disappear.
3．Factories pour waste water into rivers.
4．We must stop factories using water.
5．We should stop throwing rubbish into rivers.
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
