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The earth is covered by water. All lives on the plan need water.
Firstly, clean water is useful for us humans. We use it when we take a bath and brush our teeth as well as cook food. We also play in the water.
Secondly, all animals need clean water. When the water is not clean, animals may get sick or die, and some may have to leave their homes.
So saving water helps save the earth. If we save the water and make it clean together, we will help keep the planet safe.
| A．So how can we help these animals? |
| B．On hot days, we might swim in a swimming pool. |
| C．Lastly, plants need clean water as well. |
| D．Then why do we have to keep the water clean? |
| E．Humans also need air to breathe. |
| F．The water pollution is so serious in China. |
| G．But some water on our planet is not clean. |
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
