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B: I’m writing goodbye letters to all my friends at school.
A: That’s a good idea.
B: Well, first I write the name of a friend. Look! This one is for Sam.
A:
B: Then I write “Wishing you happiness every day and Good luck for the future” in every letter.
A:
B: About forty letters.
A:
| A．How many letters are there? |
| B．What are you doing? |
| C．What a lot of good wishes! |
| D．What are you writing in your letters? |
| E．And then? |
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
