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I walked up. What did I 1． (see)? I 2． (see) a koala mother with her baby on her back. She 3． (be) 4． (walk) slowly across the road. When she 5． (be) tired, she just 6． (sit) down in the middle of the road.
After some time, the koala mother 7． (get) up and 8． (walk) off the road. Then the cars 9． (start) to 10． (go). Koalas 11． (be) rare in the world. The Australians love them very much. They 12． (do) their best to 13． (protect) them.
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
