我市某校学生开展地理野外实践活动,同学们沿等高线地形图中虚线所示线路进行考察.读等高线地形图完成下列问题.
已知△ABC的外接圆半径为1,圆心为O,且3OA→+4OB→+5OC→=0→,则 OC→·AB→的值为( )
—Why didn't you cry for help when you were robbed (被抢劫)?
—If I opened my mouth, they might find my four gold teeth. That would be !