Grass-roots hospital基层医院
grass-roots projects基层项目
grass-roots industry草根农业
grass-roots deposit[地质] 表层矿床
grass-roots doctors基层医生
Grass-roots coaches基层教练员
grass-roots works基层工作
Grass-Roots Finance基层财政
grass-roots group草根群体
N-PLURAL(复数型名词) The grassroots of an organization or movement are the ordinary people who form the main part of it, rather than its leaders. (组织、运动的) 基层
You have to join the party at grassroots level from what I understand.
据我的了解,你得由基层组织入党。