甲状软骨没有哪项结构
A．甲状软骨上角
B．甲状软骨翼板
C．甲状软骨切迹
D．甲状软骨下角
E．甲状软骨弓
参考答案：E
Look! The people ___________ games.[ ]
A. play
B. plays
C. are playing
D. is playing
因式分解：x3﹣81x=( )
