题目

在棱长为3的正方体中，为线段中点，为线段上靠近的三等分点，则异面直线与所成角的余弦值为( )A. B. C. D. 答案：【答案】B【解析】以为坐标原点，以为轴，建立空间直角坐标系，再利用即可求解.如图建立空间直角坐标系，则知，，，，所以，，所以.故选：B.The police found that the house _______ and a lot of things _______. A. has broken into; has been stolen B. had broken into; had been stolen? C. has been broken; stolen? D. had been broken into; stolen?