问Google cloud vision api-身份验证异常

EN

using System;
using Google.Apis.Auth.OAuth2;
using Google.Cloud.Vision.V1;
using Google.Api.Gax.Grpc;
namespace blablabla
{
    class Program
    {
        static void Main(string[] args)
        {
            string filePath = @"D:\Manisha\Pictures\1.png";

            var image = Image.FromFile(filePath);

            var client = ImageAnnotatorClient.Create();
            var response = client.DetectText(image);
            foreach (var annotation in response)
            {
                if (annotation.Description != null)
                    Console.WriteLine(annotation.Description);
            }
            Console.ReadLine();
        }
    }
}