多项选择题
Prepare the tank by lining the walls with sheets of filter paper;pour the mobile phase into the tank,saturating the filer paper in the process,to a depth of 5 to 10 mm,colse the tank and allow to stand at 2012 to 2512 for Ih.(saturatedconditions).What are the purposes of the above procedure.（）
A．使得到不拖尾的斑点
B．使层析罐达到饱和条件
C．使避光
D．使保持稳定
E．使滤纸湿润