A:①②③④⑤
B:⑤④③②①
C:⑤③④①②
D:⑤②③④①
根据心脏结构图,回答下列问题.
Mary keeps talking about the party. She had a very good time,_______?
下列现象用物理知识解释正确的是( )
如图,在正三棱柱ABC﹣A1B1C1中,点D、E、F分别是BC、AC1、BB1的中点.
(1)求证:平面AC1D⊥平面BCC1B1;
(2)求证:EF∥平面A1B1C1.