谁能帮我翻译下“枪手”

ringer
n.
1. 打铃人
2. 发铃声的东西
3. 【口】(体育比赛中)作伪者(如谎报年龄或冒名顶替等)

给你个例句：
这场运动地目的是为了抓住“枪手”，即帮别人代考地学生。
The purpose of the campaign was to catch“ ringers,” students who take tests for other students.

ghost writer (a person who sits in an exam for sb. else)

This ghost writer is somebody who is hired to wirte false articles for boosting or stunting some kind of products.

passing oneself off to take an examination for another person

gunner;gunman后面再加个释义（one who sits in an exam for sb. else)
或者 a stunt gunner