已知OA→=1,OB→=3,∠AOB=5π6点C在∠AOB外且OB→·OC→=0,设实数m,n满足OC→=mOA→+nOB→则mn等于( )
They usually watch cartoons at home doing outdoor activities.
暑假期间,小安要去新疆旅游,下面是妈妈的嘱咐,不正确的是( )
A、B是自然数,并且A2+B7=1314,那么A+B=____ .