A:27,7
B:16,9
C:27,9
D:16,7
抛物线y2=4x的准线与双曲线 x2a2-y2=1a>0交于A,B两点,点F为抛物线的焦点,若△FAB为直角三角形,则双曲线的离心率为( )
澳大利亚国徽(右图)上的两种动物是 ( )
⑴My father is practising English.____ A.
⑵I'm going to study Geography in middle school.____ B.
⑶He is going to ride his bike to school.____ C.
⑷My friend Sam is going back to the UK.____ D.
⑸It's time to have lunch.____ E.