—Could you tell me _______?
—Sorry, I don't know. I was not at the meeting
A:what does he say at the meeting
B:what did he say at the meeting
C:what he says at the meeting
D:what he said at the meeting
在月季、菊的栽培中,人们常用扦插的方法.这种不经过两性生殖细胞的结合,由母体直接产生新个体的生殖方式称为____.
如图,⊙O的直径AB与弦CD交于点,AE=6,BE=2,CD=214,则∠AED的度数是( )
已知三棱柱ABC﹣A1B1C1的侧棱BB1在下底面的射影BD与AC平行,若BB1与底面所成角为30°,且∠B1BC=60°,则∠ACB的余弦值为( )