在前后

As a coelostat, MA tracks the motion of celestial objects observed at their meridian passages.

MA作为定天镜跟踪天动，望远镜在天中天前后进行观测。

The extract of Sophora japonica L. was processed by inorganic ceramic membrane, and the whole solid, effective ingredinent and flux of mebrane were examined.

用孔径为0.2μm无机陶瓷膜对槐米提取液进行微,对提取液微前后在总固、性状、指标性成分、膜通量等方面变化进行对比分析。