Scrape off the list of Field IDs from Google Forms.

ScrapeOffListOfFieldIdsFromGoogleFormsAsync.cs

// Imports you might need! ;) 
//using HtmlAgilityPack;
//using System;
//using System.Collections.Generic;
//using System.Linq;
//using System.Threading.Tasks;

private static async Task<List<string>> ScrapeOffListOfFieldIdsFromGoogleFormsAsync(string yourGoogleFormsUrl)
{
	HtmlWeb web = new HtmlWeb();
	var htmlDoc = await web.LoadFromWebAsync(yourGoogleFormsUrl);

	// Select the "input", "textarea" elements from the html content
	var fields = new[] { "input", "textarea" }; // two types of fields
	var htmlNodes = htmlDoc.DocumentNode.Descendants().
						Where(x => fields.Contains(x.Name));

	// Filter out the elements we need
	htmlNodes = htmlNodes.Where(
		x =>
		// Get all that elements contains "entry." prefix in the name
		x.GetAttributeValue("name", "").Contains("entry.") &&
		// Ignored the "_sentinel" elements rendered for checkboxes fields
		!x.GetAttributeValue("name", "").Contains("_sentinel"));
	
	// remove any duplicates (possibly caused by Checkboxes Fields)
	var groupedList = htmlNodes.GroupBy(x => x.OuterHtml);
	var cleanedNodeList = new List<HtmlNode>();
	foreach (var groupedItem in groupedList)
	{
		cleanedNodeList.Add(groupedItem.First());
	}

	// retrieve the Fields list
	var fieldIdList = new List<string>();
	foreach (var node in cleanedNodeList)
	{
		// grab the Field Id
		var fieldId = node.GetAttributeValue("name", "");
		fieldIdList.Add(fieldId);
		Console.WriteLine(fieldId);
	}

	return fieldIdList;
}