题目

TitleDateCategory —English books about Chinese Culture for Sale I have several English books about China and ChineseCulture to sell．I hope you will find these books areuseful to learn Chinese culture，such asChina 2008，The Art of Chinese Painting…etc．All of the books arefree for mail in Beijing． My mob：13810690437 My Email：hanmeismile@hotmail．com…moreJuly 27 , 2009 Books, maps DVDS —Moving Sale：Books，books，books! Price：From 10yuan．I'm leaving Beijing soon and looking tosell my books．All in English，I  have China-themed fiction．detective，sciencefictio如图，在直三棱柱ABC-A1B1C1中，AC=BC=AA1=2，∠ACB=90°，E，F，G分别为AC，AA1，AB的中点，（1）求证：B1C1∥平面EFG（2）求三棱锥B1-EFG的体积．