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1.It’s nine o’clock. It’s time for class.
2.The woman is a Chinese teacher.
3.We can see a book in the desk.
4.We can see five boys in the classroom.
5.We can see flowers in the vase.
![](http://static.xuejinqu.com/images/y-prise.png)
同类型试题
![](http://static.xuejinqu.com/images/medal.png)
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
![](http://static.xuejinqu.com/images/avatar.png)
![](http://static.xuejinqu.com/images/avatar.png)
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
![](http://static.xuejinqu.com/images/avatar.png)
![](http://static.xuejinqu.com/images/avatar.png)