As is known it was Hu Jintao president of our nation who gave lecture at the ceremony

问题补充：

As is known, it was Hu Jintao, president of our nation, who gave lecture at the ceremony of National Day

A. the; a

B. the ; /

C. a; the

D. /; a

答案：

(答案→)A. the; a

B. the ; /

C. a; the

D. /; a

解析：考查冠词。表示职位，头衔等名词，表示独一无二，前不用冠词；give a lecture作讲座，选A。