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