在asp.net mvc中，如何将htmlDropdownlist与选定值和onchange事件一起使用？

如何加载带有选定值的下拉列表？还有一个onchange事件

List<SelectListItem> environments = new List<SelectListItem>();

environments.Add(new SelectListItem { Text = "Development", Value = "DEV"});
environments.Add(new SelectListItem { Text = "Staging", Value = "STA" });
environments.Add(new SelectListItem { Text = "SNL", Value = "SNL"});
environments.Add(new SelectListItem { Text = "Production", Value = "PROD" });

 ViewData["Environments"] = new SelectList(environments, "Value", "Text", environment);

<p>Select a Deploy to: <%=Html.DropDownList("Environments", (SelectList)ViewData["Environments"], new { onchange = "this.form.action='DeployToChanged';this.form.submit()" })%></p>

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你是说在页面加载时预先选择一个吗

new SelectListItem { Text = "..", Value = "..", Selected=true}

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我假设一旦下拉列表更改，您将提交表单？我假设您不是指像Asp.net这样的服务器端事件。正当