Nelson Mandela was of South Africa from 1994 to 1999.A. presidentsB. a presidentC. Preside

问题补充：

Nelson Mandela was of South Africa from 1994 to 1999.

A. presidents

B. a president

C. President

D. our president

答案：

A. presidents

B. a president

(答案→)C. President

D. our president

解析：纳尔逊曼德拉从1994年到1999年是南非总统。此题中“总统”是官衔，作为专有名词，所以不加冠词，故选C。