单项选择题Therole of official reserves is ________ under a ________ exchange rateregime. A、enhanced; floating B、diminished; fixed C、enhanced; fixed D、None of the above apply.
单项选择题同轴承配合的轴旋转时带着油一起转动，油进入楔缝使油压升高，当轴达一定转速时，轴在轴承中浮起，直至轴与轴承完全被油膜分开，形成( )。
