腭盖高拱，龈红肿，开唇露齿下列情况的病因是：（）
A.吮指
B.咬下唇习惯
C.口呼吸
D.偏侧咀嚼习惯
E.吐舌习惯
参考答案：C
一When were you born?
一I was born ____ the morning of May 7, 1995. [ ]
A. in
B. on
C. at
D. of
数据的逻辑结构有线性结构和【 】两大类。
