[transitive]

1. (often be concerned) to affect sb; to involve sb
   影响，牵涉（某人）◆The matter doesn't concern us.
   这件事不会影响我们。◆The closure of the firm was upsetting to all concerned (= everyone involved).
   关闭公司对与此有关的各方来说都是一件令人沮丧的事。

●To whom it may concern … (only used in written English 只用於书面英语) used, for example, at the beginning of a public notice or of a job reference, when you do not know the name of the person you are writing to
敬启者