问题
单项选择题
下颌中切牙具有唇舌向两个根尖孔的只有
A．1%
B．3%
C．5%
D．7%
E．9%
答案
参考答案：E
解析： 下颌中切牙根管的唇舌径宽，直到牙根中 1/3才开始变细，向根尖逐渐缩小，大多为单根管，约10%显示唇舌向双根管。故答案为E。
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下颌中切牙具有唇舌向两个根尖孔的只有
A．1%
B．3%
C．5%
D．7%
E．9%
参考答案：E
解析： 下颌中切牙根管的唇舌径宽，直到牙根中 1/3才开始变细，向根尖逐渐缩小，大多为单根管，约10%显示唇舌向双根管。故答案为E。
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| One bright summer day, boys and girls were having a walk with their teacher near the zoo. They walked and 1 happily. After a while, they came to a 2 over the river, and they took turns to go across it. When they just reached the middle, there came a great shout of warning behind them. The teacher told them 3 , and she turned back and listened. When she heard the voice" 4 !", she knew what would happen. Before she could do anything she saw a wolf 5 towards the bridge. "Children," said the teacher,"Don't worry, don't move 6 cry." Then she ran to the back of the children 7 the wolf should meet her first. The wolf came, and its mouth was widely open. When it passed the teacher, the wolf saw a boy. It stopped and wanted to snap (咬) at the boy. When the teacher 8 this, she put her right hand into the wolf's 9 quickly. The wolf was so frightened, and it 10 at once. When people heard of it, they all spoke highly of her bravery (勇敢). | ||||
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