to be quick to act or to react to an event or situation.

The police were quick off the mark reaching the scene of the accident.

• it doesn't hurt to
• it doesn't hurt to do something
• it doesn't take a rocket scientist
• it doesn't take a rocket scientist to
• it doesn't take a rocket scientist to do something
• I tell you
• it escapes
• it escapes me
• It goes without saying.
• it goes without saying
• I thought as much!
• be off your rocker
• be off your trolley
• be of like mind
• be of one mind
• be of own making
• be of the essence
• be of two minds
• be of your own making
• be on a collision course
• be on a hiding to nothing
• be on another planet
• be on a roll
• be on ass
• be on a sticky wicket