momentously       
adverb uk/məˈmen.təs.li/ us/məˈmen.t̬əs.li/
 重大地,重要地
in a way that is very important because of effects on future events
  These goals are momentously important to Peter.
 The Security Council met momentously two years ago to agree on a resolution which led to war. 两年前,安理会召开重要会议,就一项导致战争的决议达成了一致。 
 See: momentous
 - More examples
- This was a momentously joyous occasion for us.
- More momentously, on the night of his arrival he met the woman who was to become his wife.
- It is rare that something momentously important yet wholly good happens in international life.