Asp.net mvc 回发表单时出错：“集合为只读”

我有一个5个字符串值的列表，我希望用户输入每个问题的可能答案。但当我提交表单时，会出现一个错误：集合是只读的。这里怎么了

以下是我的视图模型：

public class QuestionVM
    {
        public QuestionVM() {
            PossibleAnswers = new string[5];
        }
        public QuestionVM(Question question) : this()
        {
            ID = question.ID;
            Text = question.Text;
            IsAssociatedWithProfessor = question.IsAssociatedWithProfessor;
            IsAssociatedWithAssistant = question.IsAssociatedWithAssistant;
        }
        public int? ID { get; set; }
        public string Text { get; set; }
        public bool IsAssociatedWithProfessor { get; set; }
        public bool IsAssociatedWithAssistant { get; set; }
        public IEnumerable<string> PossibleAnswers { get; set; }
        public Question ToQuestion(ApplicationDbContext context)
        {
            Question question = new Question
            {
                Text = this.Text,
                IsAssociatedWithProfessor = this.IsAssociatedWithProfessor,
                IsAssociatedWithAssistant = this.IsAssociatedWithAssistant
            };
            //ID will be null if creating new question
            if(ID != null)
            {
                question.ID = (int) ID;
            }
            foreach (string possibleAnswer in this.PossibleAnswersVM.PossibleAnswers)
            {
                if (!String.IsNullOrEmpty(possibleAnswer))
                {
                    PossibleAnswer existingPossibleAnswer = context.PossibleAnswers.SingleOrDefault(ans => ans.Text == possibleAnswer);
                    if (existingPossibleAnswer == null)
                    {
                        PossibleAnswer ans = new PossibleAnswer { Text = possibleAnswer };
                        context.PossibleAnswers.Add(ans);
                        question.PossibleAnswers.Add(ans);
                    }
                    else
                    {
                        question.PossibleAnswers.Add(existingPossibleAnswer);
                    }
                }
            }
            return question;
        }
    }

部分意见：

@Html.EditorFor(model => model.PossibleAnswers, "PossibleAnswers")

和模板：

@model IEnumerable<string>
@{
    ViewBag.Title = "PossibleAnswers";
}

@foreach (var str in Model)
{
       @Html.TextBoxFor(m => str)
}

---

确保您遵循了以下提示：

只需在Views/Shared/EditorTemplates文件夹中添加编辑器模板 通过为应用程序定义合适的@models来使用参数化模板，以便更容易地检测。 在需要时使用[UIHintTemplateName]引导剃须刀。

---

看一看。

你有错误吗？我没有。当我运行应用程序时，编辑字段不会出现。您的编辑是否修复了它，还是仍然存在问题？我将以下内容添加到我的问题视图模型中：public QuestionVM{PossibleAnswers=new string[5]；}，因为我希望用户输入5个输入。它以前没有呈现，因为我的列表是空的。但现在还有另一个问题，当我提交表单时，会出现一个错误：集合只读。完整的错误堆栈跟踪可能会有所帮助。

@model IEnumerable<string>
@{
    ViewBag.Title = "PossibleAnswers";
}

@foreach (var str in Model)
{
       @Html.TextBoxFor(m => str)
}