preformed

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

前造影以了解泪囊大小和阻塞部位，以选择最手适应证。

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

安装时将互连铜排卸下，穿间预留长方孔，固定在相邻两接地铜排上。