-- I’m thirsty. I want something to drink. What about you?
-- OK, let's go and buy some _________.
A:orange
B:oranges
C:bread
D:chocolate
(Ⅰ) 证明:CD⊥平面A1OC;
(Ⅱ) 若平面A1BE⊥平面BCDE,求平面A1BC与平面A1CD夹角(锐角)的余弦值.
手电筒的光线是____线.