如何在c#中调用异步web服务？

async Task<string> GetDataAsync()
{
    // 异步获取数据的逻辑
    // 返回异步操作的结果
}

HttpClient client = new HttpClient();
HttpResponseMessage response = await client.GetAsync("http://example.com/api/data");

string responseBody = await response.Content.ReadAsStringAsync();

async Task<string> GetDataAsync()
{
    HttpClient client = new HttpClient();
    HttpResponseMessage response = await client.GetAsync("http://example.com/api/data");
    string responseBody = await response.Content.ReadAsStringAsync();
    return responseBody;
}

async void CallWebService()
{
    string data = await GetDataAsync();
    // 处理返回的数据
}