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Bobby: The Earth is our home.
Sam: You’re right. But not all students know this.
Bobby:
Sam: Let’s make a poster and tell them about it.
Willy: Good idea!
Sam: Let me draw the Earth first. Then some green trees, a river...
Willy: Let me draw a rubbish bin.
Bobby: OK. What a nice poster!
Sam: Let’s put in at the school gate.
Bobby: Great! All students should protect the Earth and keep it clean.
| A．What can we do? |
| B．Where can we put it? |
| C．We should protect it. |
| D．Everyone shouldn’t litter. |
| E．We can draw pictures on it. |
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
