题目

若=a，=b，a与b不共线,则∠AOB平分线上的向量为（    ） A.                             B. C.                       D.λ(),λ由确定 答案：答案:D解析:如图，设a方向上的单位向量为i=，b方向上的单位向量为j=,以i、j为邻边作平行四边形OA′CB′,则=i+j且OC为∠AOB的平分线.∴与共线.∴=λ=λ(+）.He made another wonderful discovery, ________ of great importance to science. A. which I think is　　　　　　 B. which I think it is C. which I think it　　　　　　  D. I think which is