具有促进视觉细胞内感光物质合成与再生的维生素是（）
A.维生素PP
B.维生素B1
C.维生素A
D.维生素D
E.维生素C
参考答案：C
The original building was erected in 1710, but this structure has been largely transformed and extended, the present hotel______in 1910.
A．was completed
B．to have been completed
C．having been completed
D．completed
所有上市交易的股票和债券都是证券经纪业务的对象。( )
