持续牵引最常用的方法是（）
A.皮肤牵引
B.牵引带牵引
C.骨盆牵引
D.枕颌带牵引
E.骨牵引
参考答案：E
--- is “Animal World” shown on CCTV-2? ---Every week
A．How long
B．How soon
C．How often
D．How many times
