linq 剔除已经添加过的关键字

//begin 剔除已经添加过的关键字
HashSet<string> mHashSet = new HashSet<string>(mKeywordUsingLst.Select(m => m.Word).Distinct());
List<RecommendWord> mRecommendWordLstExcepted = mRecommendWordLst.Where(m => mHashSet.Contains(m.Word) == false).ToList<RecommendWord>();
//end 剔除已经添加过的关键字

或

mRecommendWordLst.Except()