根据下列短文内容，在短文后的空格处填上一个恰当的词，使短文完整、通顺。

     It was a very cold morning. Some children were    1    on the ice. It was snowing    2   , but they

enjoyed    3    there. Mike, a tall boy, skated fast and he didn't see that there was a    4     in the ice. He

   5    into the water. The other children called out    6    for help. Just then, a young man    7    quickly.

He    8    into the water without    9    off his clothes. Mike was   10   .

已知一组数据：3，3，4，4，5，6，6，6，这组数据的中位数是______．