问题 选择题 已知空间两点A(4,a,-b),B(a,a,2),则向量AB=( )A.(a-4,0,2+b)B.(4-a,0,-b-2)C.(0,a-4,2+b)D.(a-4,0,-b-2) 答案 ∵A(4,a,-b),B(a,a,2)∴AB=(a-4,a-a,2-(-b))=(a-4,0,2+b)故选A