```python def add(x, y): return x + y def subtract(x, y): return x - y def multiply(x, y): return x * y def divide(x, y): if y == 0: return "除数不能为0" else: return x / y print("选择运算：") print("1.加法") print("2.减法") print("3.乘法") print("4.除法") choice = input("输入你的选择(1/2/3/4):") num1 = float(input("输入第一个数字: ")) num2 = float(input("输入第二个数字: ")) if choice == '1': print(num1, "+", num2, "=", add(num1, num2)) elif choice == '2': print(num1, "-", num2, "=", subtract(num1, num2)) elif choice == '3': print(num1, "*", num2, "=", multiply(num1, num2)) elif choice == '4': print(num1, "/", num2, "=", divide(num1, num2)) else: print("非法输入") ```