A:秦始皇
B:张骞
C:汉武帝
D:班超
I haven't seen my grandma for a long time. I can't help her very much.
人类缺乏维生素A易患( )
如果cosπ+A=-12,那么sinπ2+A=( )
6月22日,下列城市中白昼最长的是( )