The army convoyed the supplu trucks to the center of the battle. (battle 战斗，与...作战，战役)
defend vt. 防护
escort vt.护送(accompany)
a bodyguard escorted the celebrity around town. (celebrity 名流，名声，名人)
preserve vt. 保存(keep,save, maintain)
Max eats only good things, hoping to preserve his health.
retain vt.保留 (hold, reserve, withhold, keep)
We retained the original fireplace when we decorated the room.