A:It's boring.
B:On TV.
C:I watch it every day.
如图,在正方体ABCD﹣A1B1C1D1中,
(1)求证:AD1⊥平面CDA1B1;
(2)求直线AD1与直线BD所成的角.
能确定某学生在教室中的具体位置的是( )