Igor was both the 15th highest and the 15th lowest in a tennis tournament. How many people were in the tournament?
    A：28
    B：29
    C：30
    D：31
    E：32
    答案：B
    思路：正數(shù)第十五加上倒數(shù)第十五個，應(yīng)該是30個人，但是正數(shù)和倒數(shù)的第十五名都是一個人，所以，答案應(yīng)該是29個人。