When you see an English film or talk with native speakers, observe their facial expressions and g____.
如图,在正六边形ABCDEF中,连接AE,则tan∠1=____ .
下列情形中,哪一项是法定义务( )
已知直线l与直线2x﹣3y+4=0关于直线x=1对称,则直线l的方程为( )