She was____busy____go fishing with me.
对任意两个非零的平面向量α→和β→,定义α→∘β→=α→·β→β→·β→.若平面向量a→,b→满足|a→|≥|b→|>0,a→与b→的夹角θ∈0,π4,且a→∘b→和b→∘a→都在集合n2|n∈Z中,则a→∘b→=