BTL       
 noun [ U ] UK uk/ˌbiː.tiːˈel/ us/ˌbiː.tiːˈel/
 购房出租(buy-to-let 的缩写)
abbreviation for  buy-to-let 
  BTL investors 购房出租的投资者  
the BTL market 购房出租市场  
a big boom in BTL 购房出租热 
 - More examples
 - mortgage lenders specializing in BTL
 - Flats are the housing type most favoured by BTL investors.
 - They offer low interest rates on BTL mortgages.
 
BTL       
adjective, adverb UK uk/ˌbiː.tiːˈel/ us/ˌbiː.tiːˈel/
 (also btl)读者留言(below the line 的缩写,指读者在网络文章、博客等下方发表的讨论或回复。) 
abbreviation for below the line: used to describe discussions or replies from readers that are published below an internet article, blog, etc.
  I never read the BTL comments. 我从来都不看读者留言。 
 Some of the people commenting BTL obviously hadn't even read the piece. 一些留言发表评论的人显然根本没有读过这篇文章。 
 - More examples
 - Love them or hate them, BTL comments have changed journalism.
 - Some of the btl commenters were really vicious.
 - As many people have pointed out BTL, there are factual errors in this column.
 - There's quite an interesting discussion BTL.