下列哪一种牙脱位最常发生牙髓坏死（）。
A.牙完全脱位
B.牙部分脱位
C.嵌入性脱位
D.牙颊向移位
E.牙舌向移位
参考答案：C
生态系统信息流的特点及作用。
The table above shows the one-way driving distance, in miles, between four cities: P, Q, R, and S. For example, the distance between P and Q is 144 miles. If the round trip between S and Q is 16 miles further than the round trip between S and R, and the round trip between S and R is 24 miles less than the round trip between S and P, what is the value of X ？（）
A. 174
B. 182
C. 186
D. 348
E. 364
