Not only ________ give people relaxation and pleasure, but ________ increase their knowledge of any kind.

A．can travel; it can

B．travel can; can it

C．can travel; can it

D．travel can; it can

回力卡环适用于

A．缺陷前部的基牙

B．间隔缺失的基牙

C．后牙游离缺失末端基牙

D．后牙非游离缺失的基牙

E．孤立并向近中郏（舌）侧倾斜的最后磨牙