造成我国冬季南北温差大的主要原因是 ( )
A:海陆位置
B:季风影响
C:地形因素
D:纬度位置
——Excuse me, could you tell me ?——Go along this street until you see some buildings with golden roofs.
①AB∥CD;②AB=BC;③AB⊥BC;④AO=OC.其中正确的结论有( )