C# Xamarin Android HttpClient保持活动状态不工作

我正在使用Xamarin.Android和PCL。在我的PCL中，我使用HttpClient获取HTTP请求或将其发布到API。 我想对多个HTTP请求使用同一个HttpClient实例，并使用keep-alive

以下是我的测试代码：

HttpClient c = new HttpClient(new HttpClientHandler { AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate });
c.Timeout = new TimeSpan(0, 0, 15);
c.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", bufferItem.m_sAutorisationBasic);
c.DefaultRequestHeaders.Add("Connection", "Keep-Alive");

for (int i = 0; i < 5; i++)
{
    HttpRequestMessage t = new HttpRequestMessage(HttpMethod.Get, new Uri(bufferItem.m_sURL));
    HttpResponseMessage r = await c.SendAsync(t);
}

有人能帮忙吗？请问我做错了什么

HttpResponseMessage r = await c.SendAsync(t);
string content = await r.Content.ReadAsStringAsync();