—Do you miss your parents far away?

—Yes, very much. They _________ the hometown for over two years.

A．left

B．have left

C．were away from

D．have been away from

冷沉淀主要成分有

A．因子Ⅷ促凝血活性

B．因子IX促凝血活性

C．因子XI促凝血活性

D．因子XII促凝血活性