intervener

interfere, intervene, meddle

1. I am powerless to intervene in the matter.
   我对调停此事无能为力。
2. I intervened on her behalf to try to get the decision changed.
   我为她力争，以求改变决定。
3. I will come if nothing intervenes.
   假若没有别的事，我一定来。
4. I was alone during intervening years.
   这期间的若干年里，我一直一个人。