问题
单项选择题
龈上牙石是
A．不能直接观察到牙石
B．质地坚硬的牙石
C．附着较紧，较难去除的牙石
D．沉积于牙周袋内的牙石
E．沉积于龈缘以上牙面的牙石
答案
参考答案：E
解析：位于龈缘以上牙面的牙石称为龈上牙石，肉眼可见，质地中等硬度。相对于龈下牙石则附着较松、较易去除。
搜题请搜索小程序“爱下问搜题”
龈上牙石是
A．不能直接观察到牙石
B．质地坚硬的牙石
C．附着较紧，较难去除的牙石
D．沉积于牙周袋内的牙石
E．沉积于龈缘以上牙面的牙石
参考答案：E
解析：位于龈缘以上牙面的牙石称为龈上牙石，肉眼可见，质地中等硬度。相对于龈下牙石则附着较松、较易去除。
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| There are different 1 of animals in the zoo. They don't have to 2 food by themselves. We can see the zoo keepers give them food to 3 . They just eat, walk and sleep 4 day. So many of us may think that the animals there are 5 and lucky. But most of them are sad. Why? They're no 6 free! Animals like elephants, monkeys and tigers usually live freely and happily in forests or mountains. Tigers, for 7 , run, jump, play with their children and catch small animals for food. But now they have to stay in small room in the zoo. Their life in the zoo is quite 8 from their life in the forests. Now many of us think more animals should go 9 to forests and mountains so 10 the earth will become better. | ||||
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