It was January the_________he came here last time.

A．thirty-one that

B．thirty first that

C．thirtieth-one when

D．thirty first when

按照纬向对称的经圈环流模式，哈得来环流的上升支的位置具有季节性位移，北半球夏季位于（）附近，冬季位于（）附近。