— The old photos remind me of my best friends.
—Then, who are they?
A: make me worry about
B: make me look at
C: make me think of
(1)81+-273+-232
(2)(﹣3)2﹣|1﹣3|+22﹣53
(3)求x值:(3x+1)2=16
(4)(x﹣2)3﹣1=﹣28.
如图,正方形ADEF与梯形ABCD所在的平面互相垂直,AD⊥CD,AB∥CD,AB=AD=2,CD=4,M为CE的中点.
(I)求证:BM∥平面ADEF;
(Ⅱ)求证:平面BDE⊥平面BEC.