A.8                   B.5                     C.3                     D.0

A.n=3                               B.n=4

C.n=3或n=4                      D.n=3或n=4或n=5

A.＞                  B.＜

C.=                  D.大小关系不定

A.                                     B.n(n-1)(n-2)·…·(n-m)

C.                          D.

A.一定是奇数                                     B.一定是偶数

C.奇偶性由n的奇偶性来决定                 D.以上结论都不对

A.            B.            C.            D.

(1)；

(2)；

(3).

A.36                   B.30                    C.24                   D.12