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;
}
}