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Do you know China’s Teeth Care Day? It 1． on September 20 every year. It began in 1989. Its aim is to take good care of people’s teeth.
There are thirty—eight students in Wang Bin’s class, and eleven of them have tooth problems 2． bring them much trouble.
Mao Kang said, “I had three bad teeth. Each tooth 3． me four hundred yuan, and I had to see the dentist five 4．.”
Liu Jian said, “Something is wrong with my front teeth, I don’t like to open my mouth. My classmates say my teeth look like an old woman’s, I’m sad to hear that. And I can’t speak clearly now.”
Do you have good teeth, my friends? 5． you want to take care of your teeth, please do these:
◆Brush your teeth at 6． once a day. If you can, brush them after every meal.
◆Brush all your teeth, do not 7． brush the front ones.
◆Brush your teeth 8． and carefully. Spend four minutes or more each time.
◆Do not use your teeth 9． tools to open bottles. It's very easy to hurt your teeth to do such jobs.
◆Use soft toothbrushes. Get a new toothbrush every three months.
◆Eating and drinking is also important to your teeth. Eat lots of fruits and vegetables and drink water. Try not 10． Coke and other drinks.
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
