楼主你好：
10、9、7、9：电脑无解
3、1、12、11：
1: (3 × (1 + 11) - 12
2: 3 × (1 + 11) - 12
3: 3 × 12 -(1 + 11)
4: (3 × 12) - (1 + 11)
5: 3 × 12 - 1 - 11
6: (3 × 12) - 1 - 11
7: (3 × 12 - 1) - 11
8: (3 × 12) - 1) - 11
9: 3 × 12 -(11 + 1)
10: (3 × 12) - (11 + 1)
11: 3 × 12 - 11 - 1
12: (3 × 12) - 11 - 1
13: (3 × 12 - 11) - 1
14: (3 × 12) - 11) - 1
15: (3 × (11 + 1)) - 12
16: 3 × (11 + 1) - 12
17: (1 + 11) × 3 - 12
18: (1 + 11) × 3) - 12
19: 12 × 3 -(1 + 11)
20: (12 × 3) - (1 + 11)
21: 12 × 3 - 1 - 11
22: (12 × 3) - 1 - 11
23: (12 × 3 - 1) - 11
24: (12 × 3) - 1) - 11
25: 12 × 3 -(11 + 1)
26: (12 × 3) - (11 + 1)
27: 12 × 3 - 11 - 1
28: (12 × 3) - 11 - 1
29: (12 × 3 - 11) - 1
30: (12 × 3) - 11) - 1
31: (11 + 1) × 3 - 12
32: (11 + 1) × 3) – 12
13.1.4.11：电脑无解
8.9.10.11：电脑无解
6.8.13.7：电脑无解