与字段匹配的列表

我需要匹配从中返回的字段 fields 具有 sometext .

public interface IProjectData
    {
        string field { get; set; }
        string fieldName { get; set; }
        string type { get; set; }
    }

    public class ProjectData : IProjectData
    {
        public ProjectData();

        public string field { get; set; }
        public string fieldName { get; set; }
        public string type { get; set; }
    }
var fields = new List<MarinaAPI.MarinaAPI.ProjectData>();
fields = SomeClassApi.Get(code, "TG");
var selectedField1 = fields.Single(x => x.field.Contains("sometext"));

但我有一个错误:

如何更正代码以获取 field 与值匹配 一些文字