下列有关小动物研究的叙述,正确的是( )
根据所给首,与出所缺单词。I can see a v ____ tape on the desk.Li Gang likes m ____ , but he doesn’t music.The p ____ is very good. I also want to buy one.This r____ is very big, but that one is very small.I n ____ a pen, two pencils and some books.
如图,在多面体ABCDEF中,底面ABCD是边长为2的正方形,四边形BDEF是矩形,平面BDEF⊥平面ABCD,BF=3,G和H分别是CE和CF的中点.
(Ⅰ)求证:AC⊥平面BDEF;
(Ⅱ)求证:平面BDGH∥平面AEF;
(Ⅲ)求多面体ABCDEF的体积.