preformed

Dacryocystography was preformed in all patients before operation to confirm the obstructive sity and the size of lacrimal sac.

术前造影以了解泪囊的大小和阻塞的部位，以选择最佳手术适应。

When installation, unlade the join copper bus bar, through the preformed long-square hole, fixing it on the main grounding bus bar.

时将互连铜排卸下，穿柜间预留的长方孔，固邻两柜的主接地铜排上。