—________is the price of your father’s computer?
—6, 800 yuan.
A:How much
B:How many
C:What
D:How
被的人们称为“绿色金子”的是( )
如图,直三棱柱ABC﹣A1B1C1,底面△ABC中,CA=CB=1,∠BCA=90°,棱AA1=2,M、N分别是A1B1、A1A的中点.
(1)求BN→的长;
(2)求cos(BA1→•CB1→)的值;
(3)求证A1B⊥C1M.
b____s