It must be kept in mind that _______ lifelong study can you survive in the high competitive society.

A．until when

B．until then

C．only through

D．only when

资产阶级经济学家认为，区分固定资本和流动资本的依据是物体本身的( )

A．价值大小

B．耐用性

C．流动性

D．使用性能