A:关于极轴所在直线对称
B:重合
C:关于直线θ=π2(ρ∈R)对称
D:关于极点对称
—— __________ do you chat by QQ with your friend in Shanghai every week?——Two hours. I have much homework to do every day.
下列生物的生殖方式属于有性生殖的是( )
竿高与影长成正比例吗?