题目:
1. 用户可以以Mile、Yard、Feet、Inch为单位来表示一个长度。
2. 可以对比任意两个长度的相等性:
1 Mile == 1 Mile
1 Mile == 1760 Yard
1 Yard == 3 Feet
1 Feet == 12 Inch
3. 任意两个长度可以进行加法运算 ,例如:
13 Inch + 11 Inch = 2 Feet
3 Feet + 2 Yard = 3 Yard