用+.-.X./怎样使以下算式成立：1 2 3 4 5 6 7=51

1 :1 + 2 + 3 - 4 + 56 - 7 = 51
2 :1 + 2 - 3 + 4 + 5 + 6 * 7 = 51
3 :1 + 2 * 3 + 45 + 6 - 7 = 51
4 :1 + 2 * 34 - 5 - 6 - 7 = 51
5 :1 + 23 + 4 + 5 * 6 - 7 = 51
6 :1 - 2 + 34 + 5 + 6 + 7 = 51
7 :1 * 2 + 3 + 45 - 6 + 7 = 51
8 :1 * 2 + 3 * 4 + 5 * 6 + 7 = 51
9 :1 * 2 + 3 * 4 - 5 + 6 * 7 = 51
10 :1 * 2 + 3 / 4 * 56 + 7 = 51
11 :1 * 2 * 3 - 4 + 56 - 7 = 51
12 :1 / 2 + 345 / 6 - 7 = 51
13 :12 * 34 / 56 * 7 = 51
14 :12 / 3 - 4 * 5 + 67 = 51
Press any key to continue
1 :-1 + 2 + 3 - 4 * 5 + 67 = 51
2 :-1 + 2 - 3 + 4 + 56 - 7 = 51
3 :-1 + 2 - 3 * 4 - 5 + 67 = 51
4 :-1 + 2 * 3 + 45 - 6 + 7 = 51
5 :-1 + 2 * 3 * 45 / 6 + 7 = 51
6 :-1 + 2 * 3 / 4 * 5 * 6 + 7 = 51
7 :-1 - 2 + 3 + 4 + 5 + 6 * 7 = 51
8 :-1 - 2 * 3 + 45 + 6 + 7 = 51
9 :-1 - 2 * 3 - 4 - 5 + 67 = 51
10 :-1 / 2 * 3 + 45 / 6 * 7 = 51
Press any key to continue

(1+2+3+4)*5-6+7=51