How to add a dropdownlist in Contact us page?

Dear all,

I am using Nop 3.1 version, I would like to add a Dropdownlist in Contact us page,
and it could change the Contact us Email Title which I want to seperate the question type.

Does it can be added in the contactus.cshtml? or It will need edit others files?
Please tell me how to add this function, and thank you very much.

You need to change view side and source code as well.
Look into Views/Customer/Register.cshtml

but I am not familiar with CSHTML code,
is there another way to add a simply contact us email post in the nopcommerce pages?

Silver
A little more information , if you would be so kind..

I just did this myself (nop 3.1)
the Model, View and Controller all have to change:

Model - add something like this to ContactUsModel.cs

        
public ContactUsModel()
 {
            this.SubjectDD = new List<SelectListItem>();
            SubjectDD.Add(new SelectListItem() { Text = "Order Status Inquiry", Value = "Order Status Inquiry" });
            SubjectDD.Add(new SelectListItem() { Text = "Billing Inquiry", Value = "Billing Inquiry" });
            SubjectDD.Add(new SelectListItem() { Text = "Return Inquiry", Value = "Return Inquiry" });
            SubjectDD.Add(new SelectListItem() { Text = "Other Question", Value = "Other Question" });
 }

        
 [NopResourceDisplayName("ContactUs.Subject")]
 [AllowHtml]
 public string Subject { get; set; }
  [NopResourceDisplayName("ContactUs.Subject")]
 public IList<SelectListItem> SubjectDD { get; set; }

View -

<div>
  @Html.LabelFor(model => model.SubjectDD)
  @Html.DropDownList("Subject", Model.SubjectDD);
</div>

Controller -- CommonController.ContactSent(...)

String subject = model.Subject ;

No Warranties - your mileage may vary . . .

I found the easiest to have a dropdown by just changing following the following line in Presentation\Nop.Web\Views\Common\ContactUs.cshtml:
@Html.TextBoxFor(model => model.Subject, new { @class = "subject", placeholder = T("ContactUs.Subject.Hint") })

to
                                <select id="Subject" name="Subject">
                                    <option value="volvo">Volvo</option>
                                    <option value="saab">Saab</option>
                                    <option value="mercedes">Mercedes</option>
                                    <option value="audi">Audi</option>
                                </select>