为了使对象判空更加美观，你应该使用此扩展

/// <summary>
/// Object扩展
/// </summary>
static class ObjectExtensions
{
    /// <summary>
    /// 判断实例对象是否为Null
    /// </summary>
    /// <param name="obj">实例对象</param>
    /// <returns></returns>
    public static bool IsNull(this object obj)
    {
        return obj == null;
    }
}