-- Which hobby do you think the least time?
-- Collecting stamps.
A:takes up
B:tidies up
C:gives up
D:makes up
①肝细胞;②茎形成层细胞;③蓝藻;④有丝分裂前期;⑤有丝分裂后期;⑥有丝分裂末期
在ΔABC中,a=23,b=22,B=45°,则A等于()