A:电视遥控器
B:军用雷达
C:行车导航器
D:医用B超探测仪
已知等差数列{an}的公差为2,若a1,a3,a4成等比数列,则a2=( )
— Why are you so ________?
— I am watching an ________ basketball game.
如图,AB∥CD,直线EF与AB,CD分别相交于点E、F,EP平分∠AEF,FP平分∠EFC.