单选题
In how many different ways can 3 people be assigned to fill 3 different positions so that each person is assigned to exactly one position?
(A) Twelve (B) Nine
(C) Six (D) Three
(E) One
(A) Twelve (B) Nine
(C) Six (D) Three
(E) One
【正确答案】
C
【答案解析】[解析] 把这三个职位固定为1，2，3，然后求这三个人有多少种不同的排列来占取这三个位置，其排列数为