whois sfenglishlessons.com/members/chesthill47/activity/596461/

Domain:
Turn off cache
Try for webbased whois (don't expect it to work yet)
sfenglishlessons.com/members/chesthill47/activity/596461/
checking....sfenglishlessons.com/members/chesthill47/activity/596461/
   $ whois sfenglishlessons.com/members/chesthill47/activity/596461/
No whois server is known for this kind of object.