在咀嚼过程中，磨损的定义是（）
A.牙面与食物之间的摩擦而造成牙齿缓慢地渐进性消耗
B.牙面与牙面之间的摩擦而造成牙齿缓慢地渐进性消耗
C.牙面与外物机械摩擦而造成牙体损耗
D.牙面与外物机械摩擦而产生的外物机械损耗
E.牙面与牙面之间摩擦而造成牙齿迅速损耗
参考答案：C
解析：在咀嚼运动中，磨损是指牙面与外物机械摩擦而造成牙体损耗。选择C。
| 完形填空。 | ||||
| School students in China have been learning dance for a year since 2008. Are they doing well? On September, 2008, a dance competition was 1 in Xi'an. Let's take a look. More than 2,500 students from 40 schools 2 the competition. The Middle School affiliated (附属的) to Xi'an Jiaotong University was the 3 of all the junior teams. The 100 students of the school were happy to 4 the first prize. They made their dance special 5 a "five Olympic rings" pattern (形状). They also 6 the waltz and the traditional yangge dance. No pains, no gains. The students said they had been practising for 7 half a year. "We were nervous at first 8 we didn't know each other," said Zeng Jingyi, a 13-year-old girl. "What's more, the boys were clumsy (笨拙的) and often stepped on the girls' 9 !" Only practice makes perfect. The students practiced more than three hours a day."Sometimes I saw boys playing basketball in the playground," said Xu Rui, a 13-year-old boy. "How I wanted to join them! But I didn't. Dancing can be 10 too. We should work hard for our school's honor." | ||||
|