选出与句子相符合的图片。
A. B. C. D.
(____) 1. Lily is a girl. She is my new friend.
(____) 2. He is from Shandong. He's a student..
(____) 3. Miss White is my new teacher.
(____) 4. The boy is four years old. He's from the USA.
(Ⅰ)求证:A1B⊥BC;
(Ⅱ)若AD=AB=3BC,∠A1AB=60°,点D在平面ABB1A1上的射影恰为线段A1B的中点,求平面DCC1D1与平面ABB1A1所成锐二面角的大小.