I liked flying a kite ______ I was a child. [ ]
A. before
B. since
C. when
D. until
答案:C
抑制上颌骨生长(ANB>5°)时,口外弓每日戴用时间为()
A.8~12小时
B.12~14小时
C.24小时
D.10小时
E.14小时以上
出铁口烧穿的原因