题目

He will never forget the day ________ he spent with his students. A．when                                 B．which C．during which                         D．on which 答案：解析：分析句子结构可知，所填词引导一个定语从句，修饰先行词the day，并在从句中作spent的宾语，故选项B正确。 答案：B如图，在正方体ABCD-A1B1C1D1中，AB=1（1）求异面直线A1B与 B1C所成的角；（2）求证：平面A1BD∥平面B1CD1．