He used to __________ in a small village, but he has been used to __________ in a big city now.
A:live; living
B:live; live
C:living, living
假如你是一名导游,现英国一旅游团要参观我国元谋人遗址,你应该带他们去( )
过双曲线的一个焦点F2作垂直于实轴的弦PQ ,F1是另一焦点,若∠PF1Q=π2,则双曲线的离心率e等于( )
如图,已知点A,C在反比例函数y=ax(a>0)的图象上,点B,D在反比例函数y=bx(b<0)的图象上,AB∥CD∥x轴,AB,CD在x轴的两侧,AB=3,CD=2,AB与CD的距离为5,则a﹣b的值是 ____ .