A:Neither, have to
B:Either, have to
C:Neither, had to
D:Either, had to
某兴趣小组想在本周星期六到郊外山地进行爬山活动,活动前需要准备好行动方案,应选下列哪种地图( )
速度(m•s﹣1)
0.08
0.16
0.24
0.32
电流I/A
0.2
0.4
0.6
0.8
对平面上任意一点(a,b),定义f,g两种变换:f(a,b)=(a,﹣b).如f(1,2)=(1,﹣2);g(a,b)=(b,a).如g(1,2)=(2,1).据此得g(f(5,﹣9))=( )