The name of the Belarusian currency comes from the Russian rouble and was left after the collapse of the Soviet monetary system and Belarus "refusal to introduce a national currency."

白俄罗斯的货币的名称来源于俄罗斯货币—卢布，苏联货币体系崩溃后以留下来的；白俄罗斯却拒绝发行自己的民族货币。

youdao

The ruble or rouble (currency code RUB) is the currency of the Russian Federation and Belarus (and formerly, of the Soviet Union and the Russian Empire).

卢布（货币代码RUB）是俄罗斯联邦和白俄罗斯（以前是苏联和俄罗斯帝国）使用的货币。

youdao

Meanwhile, the Russian rouble weakened as a sharp midday sell-off on the Moscow bourse prompted foreign investors to repatriate their cash.

FORBES: Magazine Article

For the Russian rouble, Nomura thinks the ruling tandem has perhaps chosen the worst possible moment to unveil its plans for a role reversal.

FORBES: Mixed Views On Russian Leaders' Role Reversal; Finance Minister Resigns

The Singapore dollar and the Russian rouble are managed by a range, instead of one-way direction, and so are also good candidates for QE play.

CNN: QE3 triggers fear of new currency wars