He found it hard for Alan to focus on his teachers for longer than five minutes, _________ if the lecture was boring. 

Recent studies have discovered that fathers uniquely contribute to the development of their children, _____ in low income families.

I’m certain David’s told you his business trouble. ________, it’s no secret that he owes a lot of money to the bank..

Netizens called the fashionable homeless man the “beggar prince”, or, ____________, “Brother Sharp”.

I must go now. _____, if you want that book I'll bring it next time.