A:①②③
B:①③④
C:①②④
D:②③④
△ABC外接圆的半径为1,圆心为O,且2OA→+AB→+AC→=0→,|OA→|=|AB→|,则CA→•CB→等于( )
— ______ I have some more cake?— No, I'm afraid you can't.