7.85﹣4.7+2.15﹣4.3
193.2÷6.9﹣1.9×2.5
1.25×3.2×2.5×4.9
4.97×4.97+4.97×4.03+4.97
（3.12+0.9）÷（8.5﹣5×1.1）
[5+（17.9﹣1.74÷0.6）]×8.5．