The education of _____ young has become _____ hot and serious topic in the present society.

A．the; /

B．a; the

C．/; the

D．the; a

后牙为远中错胎，前牙深覆盖，其矫治原则为

A．矫治前牙反胎

B．矫正颌间关系，推上牙弓往后，或牵下牙弓向前。或两者并用

C．缩小牙弓或结合修复治疗

D．以上都不是

E．减径或减数