方程2-3(x+1)=1去括号得( )
A:2-3x-1=1
B:2-3x+1=1
C:2-3x+3=1
D:2-3x-3=1
Jenny's teeth are not good, because she ____.
(Ⅰ)证明:平面C1CBB1⊥平面A1ABB1
(Ⅱ)若点P为A1C1的中点,求直线BP与平面A1ACC1所成角的正弦值.