A.1对 | B.2对 | C.4对 | D.无穷多对 |
x |
x-1 |
x |
x-1 |
3×2 |
2×1 |
m(m-1)…(m-n+1) |
n(n-1)…×3×2×1 |
7×6×5×4×3 |
5×4×3×2×1 |
1 |
24 |
7 |
113 |
24 |
113 |
3 |
8 |
5 |
12 |
1 |
22 |
1 |
32 |
1 |
42 |
1 |
19982 |
1 |
19992 |
1 |
20002 |
A.
| B.
| C.
| D.
|
1 |
2 |
1 |
6 |
1 |
12 |
1 |
n(n+1) |
2003 |
2004 |
4 |
5 |
1 |
4 |
1 |
3 |
4 |
5 |
7 |
9 |
3 |
4 |
1 |
0.1 |
© 2017-2019 超级试练试题库,All Rights Reserved.