Jacques Rogge, ____ president of the IOC,delivered a speech

Jacques Rogge,___president of IOC,delivered a speech at the opening ceremony of the Beijing Olympic Games on August 8,2008.
A.the B./

冠词的一些问题
Jacques Rogge ,___president of the IOC,gave a speech at the closing ceremony of ___2010 Vancouver Winer Olympic Games.
A.a;/ B./;a C.the;/ D./;the
2.I don't konw who invented __cell phone,but I think it is __most useful invention.
A.the;the B.the;a C.a;the D.a;a
答案上分别给的是D B这两个选项

Jacques Rogge, _____ president of the International Olympic Committee highly praised the opening ceremony of _____ Beijing Olympics.

[ ]

A. a; the B. /; the C. a; / D. the; the