Dictionary，hashtable如何排序

Dictionary<string,float> dic=Dictionary<string,float>();
List<KeyValuePair<string, float>> list = new List<KeyValuePair<string, float>>(dic);

list.Sort(delegate(KeyValuePair<string, float> firstPair, KeyValuePair<string, float> nextPair)
{
   return nextPair.Value.CompareTo(firstPair.Value);
}