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The Earth is our home. On Earth, there are rivers, seas and lakes. There are hills and mountains. There are plants and animals. Many years ago, the air was clean. The rivers and lakes were clean. There were a lot of fish. There were a lot of trees and animals too .
Now the Earth is dirty . The air is dirty . The rivers and lakes are dirty . There are not many fish in the water. There are not many trees on Earth. People cut down too many trees for wood . There are not many animals either. People kill them for meat and fur。
The Earth is our home. Our home is dirty . We should make it clean again . We should keep it clean .
( ) 1. The Earth was clean many years ago .
( ) 2. There were not many trees on Earth long long ago .
( ) 3. There are not many animals on Earth now .
( ) 4. People do not like animals and trees.
( ) 5. We cannot make the Earth clean again .
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
