Protesters formed 'a human chain' [=they stood next to each other with their arms linked] around the ancient tree to prevent it from being cut down.
In the United States, the President as the commander in chief is at the head of the military 'chain of command'.
I thought he really won the lottery but he was only 'pulling my chain'. [=he was only playing a joke on me]
(..) Oh,I'll probably say yes. It's just not the kind of thing you ask a guy you just met. Wow. I really think we should examine the chain of causality here. Must we? Event a- a beautiful woman stands naked in our shower. Event b- we drive halfway across town to retrieve a television set (..)2007 TvShow: The Big Bang Theory Title: Pilot Season: 1 Episode 1