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( ) （1） The students cleaned up the classroom after school.
( ) （2）The boys pushed and pulled the tables.
( ) （3） The students were not busy.
( ) （4） A girl dropped the pencil box.
( ) （5） A boy helped the girl clean up the floor.
(It was a cleaning day at school. After school, the students stayed and cleaned up the classroom. They were busy. Some boys pushed the tables, some boys carried the desks. Some girls cleaned the windows; others cleaned the floor and the blackboard. A girl wasn’t careful. She dropped the chalk box. Jenny gave her some help and cleaned it up. )
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
