正五边形的对称轴共有[ ]
A．2条
B．4条
C．5条
D．10条
答案：C
(2013·甘肃兰州、靖远名校高三模拟)Social practice is an opportunity for students to gain________better understanding of how________society operates.
A．the；the
B．the；/
C．a；/
D．the；a
