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The earth is our home. It belongs to the people all over the world. Do you hear the Earth crying? Because sometimes people pollute the environment. It makes the Earth dirtier and dirtier. People have air pollution, water pollution and land pollution. We can't pollute the Earth any longer. It is our own home. Be Friends of the Earth! We must take care of our earth. We must do something to keep the Earth cleaner and cleaner. We can do a lot for the Earth. Come on, everybody. Never leave rubbish here and there. Put rubbish into rubbish bin. Plant more trees and keep the air clean.
（1）Do we live on the Earth? _________________________________________（2）Why does the Earth cry? _________________________________________
（3）Do you want to be the Friend of the Earth? _________________________________________
（4）What can we do to keep the environment clean? _________________________________________
（5）Why do we plant trees? _________________________________________
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
