问题
单项选择题
标准群钻上的两个月牙槽应该是（）。
A.左长右短
B.左短右长
C.交错分布的
D.对称分布的
答案
参考答案：D
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标准群钻上的两个月牙槽应该是（）。
A.左长右短
B.左短右长
C.交错分布的
D.对称分布的
参考答案：D
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| It happened when I was a little girl. I can remember neither the beginning nor the end, but whenever I 1 it, tears flow down my face. When I was young, my family led a(n) 2 life in the country. As you can imagine, many country roads are difficult to walk on. One 3 we were visiting some relatives and the 4 was very bad. It began to 5 on our way back home. Dad carried me on his 6 . Mom gave her overcoat to my 7 . We walked together through the rain for more than an hour. I was fat at that time and Dad must be 8 to hold me for such a long time. He almost 9 down many times. In hope of 10 my father's burden, I tried to carry myself, 11 I achieved nothing since I was just a little kid. When we arrived home, the inside of our house was 12 with rain water. The rain had come 13 our leaky (有裂缝的) roof and water was everywhere. Mom put bowls all around the house to try to 14 the rain. Then she put me and my elder brother to 15 , carefully placing us on the remaining 16 place. I fell asleep soon. When I opened my eyes, I found Dad and Mom were 17 in chairs, both having caught bad colds. This is my very earliest 18 . Though the evening has long passed, and now we live a happy life, I won't forget the rain we 19 together. The rain, that evening, and especially my parents' 20 , will stay in my mind forever. | ||||
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