原级：troop
trooping
第三人称单数：troops
trooping的解释
第三人称复数：troops
过去分词：trooped
过去式：trooped
1. It is in corporate America trooping to Washington for trade protection to fend off this new threat.
2. trooping的解释
2. Marked by a parade and a military ceremony known as " Trooping the Color ", the celebration this year falls on June 13.