gun for

To pursue relentlessly so as to overcome or destroy.

追逐，搜捕：全力追逐以便征服或毁灭

To go after in earnest; set out to obtain

竭力谋求：热切地追求；着手去获得

gunning for a promotion.

竭力争取提升

big gun

(informal)an important or powerful person

(非正式)（重要的或有权力的）大人物

jump the gun

(informal)act before the proper or appropriate time

(非正式)在正常（或适当）的时间之前行动，过早行动

stick to one's guns

(informal)refuse to compromise or change, despite criticism

(非正式)拒绝妥协；坚持自己的立场

we have stuck to our guns on that issue.

在那个问题上我们坚持了自己的立场。

top gun

a (or the) most important person

顶级人物；最重要的人

the top guns in contention for the coveted post of chairman.

争夺为众人觊觎的主席之位的大佬们。

go great guns

To proceed or perform with great speed, skill, or success.

全速进行，大获成功：以很快的速度、高超的技巧或巨大的成功从事或完成

under the gun

Under great pressure or under threat.

处于巨大的压力或威胁之下