需求弹性系数是指（）的比值。

A.需求量变动率与价格变动绝对量

B.需求量变动率与价格变动率

C.需求量变动绝对量与价格变动率

D.需求量变动绝对量与价格变动绝对量

  _______ from his family for over two years, he is now eager to go back home.

A．Having been separated

B．Being separated

C．Separating

D．Having separated