1. （加在名词前）表示“以前的”，“前任的”
    ex- is added to nouns to show that someone or something is no longer the thing referred to by that noun. For example, a woman''s ex-husband is no longer her husband.

    e.g. ...my ex-wife.
           我的前妻
    e.g. ...ex-President Reagan.
           前任总统里根