C#中通过发射获取对象的所有属性出错, 求指导. 标红部分不能正确获取到language里面的属性值,该如何处理

C#中通过发射获取对象的所有属性出错, 求指导. 标红部分不能正确获取到language里面的属性值
首先定义了一个student类, 这个类中有有个成员speakLanguage 为language类.
namespace person
{
    class student
    {
        
        public string name { get; set; }

        public string age { get; set; }

        public language speakLanguage { get; set; }

        public string ex { get; set; }
        
    }

    class language
    {
        public string english { get; set; }
        public string chinese { get; set; }
        public string germany { get; set; }
    }
}


            student std= new student();
            std.name = "tina";
            std.age = "100";
            std.ex = "man";
            std.speakLanguage = new language();
            std.speakLanguage.chinese = "yes";
            std.speakLanguage.english = "yes";
            std.speakLanguage.germany = "no";
         {
                object[] row = new object[std.GetType().GetProperties().Length];
                foreach (PropertyInfo property in std.GetType().GetProperties())
                {
                    if (property.PropertyType != typeof(String))                    {
                        PropertyInfo[] pro=property.PropertyType.GetProperties();

                        foreach (PropertyInfo subproperty in pro)
                        {
                            object str = new object();                            str = subproperty.GetValue(property, null);
                            row[i++] = str;
                        }
                    }
                    else
                    {
                        object str = property.GetValue(std, null);
                        row[i++] = str;
                    }
                }
            }