A. girl B. He C. His D. Her E. This F. friends
l1:2x+y﹣1=0,l2:y=kx﹣5,l1⊥l2的充要条件( )
老师是我们成长路上的引路人,我们应该虚心听取老师的教诲,真诚地接受老师的批评。( )