As is known it was Hu Jintao president in our nation who gave lecture at the opening cer

问题补充：

As is known，it was Hu Jintao， president in our nation，who gave lecture at the opening ceremony of the Beijing Olympic.

A. the；a

B. the；/

C. a；the

D. /；a

答案：

A. the；a

B. the；/

C. a；the

(答案→)D. /；a

解析：

表示职位的名词president作同位语，其前不加冠词；give a lecture为固定用法，意思是“作演讲”。