Firms are keen to hold on to the people they recruit.
译文:公司渴望留住他们所招聘的人。
分析:
1.people与they recruit之间少了一个that。<mark>they recruit</mark>是定语从句，用来修饰people.
2.keen是形容词，含义是渴望的，强烈的，敏锐的