非法发球
参考答案：攻方球员不可以在发球前抖动身体，引诱对方越位。违反则罚5码。
位于椎体前面，起自颅骨，止于骶骨的韧带是（）。
A.黄韧带
B.后纵韧带
C.前纵韧带
D.棘间韧带
E.髂腰韧带
Changing rescuers while carrying out artificial respiration should be done（）.
A.without losing the rhythm of respiration
B.only with the help of two other people
C.by not stopping the respiration for more than 5 minutes
D.at ten minute intervals
