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A. No wonder the air in our hometown is becoming dirtier and dirtier.
B. The playground has become a factory.
C. More and more people can afford cars nowadays (现在).
D. Have you heard the news?
E. When we were young, the air was very clean.
Lisa and Ben live in a city. When they were young, they always played in the playground.
Lisa: 1．
Ben: What’s news?
Lisa: 2．
Ben: Oh, my God! 3．
Lisa: Yes. And one of the main reasons is those factories.
Ben: 4． That’s another reason.
Lisa: Yes. 5． But now the air sometimes smells bad.
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
