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Mary: Hello, Lucy! 1． are you doing?
Lucy: I am sending some postcards. How 2． you?
Mary: I’m sending a letter. Where are you sending your postcards?
Lucy: I’m sending them 3． America. And where are you sending your letter?
Mary: I’m sending it to Canada.
Lucy: How 4． are the stamps?
Mary: I think they are ten yuan or more.
Lucy: That’s too expensive（昂贵的）.
Mary: I think so.
Lucy: Why not send an email on the 5．?
Mary: That’s a good idea. Let’s go and find a computer.
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
