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Alex is telling some traffic rules to Tim on the way to the bookstore.
Look at the traffic lights. You can see there are three kinds of lights: yellow, red and green. Red means stop and wait, yellow means slow down and stop, green means go. When you go at the crossing, you must obey(遵守) it. In China, you can go or drive on the right side of the road. So you must know and remember the traffic rules.
1．There are 3 traffic lights: red, black and green.2．Red means slow down and stop.
3．You must obey the traffic rules when you go at a crossing.
4．In China, you can drive on the right side of the road.
5．You don’t need to know the traffic rules.
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
