Concurrency Series: Why do I get blocked when no one has locked the row(s) being queried?

Please refer to https://blogs.msdn.com/b/sqlcat/archive/2011/02/20/concurrency-series-why-do-i-get-block-when-no-one-has-locked-the-row-s-being-queried.aspx for details

Thanks

Sunil Agarwal