富液中常有铁锈等杂质，经过滤后杂质不会继续在系统内循环，可以提高胺液的纯度。
参考答案：对
证券交易所管理人员可以开立股票账户。
The relative L/C should be issued through a third country bank in Italy ______ the sellers.( )
A．available by
B．available to
C．acceptable by
D．acceptable to
