古罗马的时尚男女曾经把穿着中国的丝绸服饰作为一种荣耀，该事件最早发生于[ ]

A．战国

B．西汉

C．东汉

D．秦朝

By the time he was ten,Edison______experiments in chemistry.

A．had already done　　　　

B．already had done

C．was already doing　　　　

D．already did