bolt

牛津：

 

• shut/close the stable door after the horse has bolted = try to prevent something when it is too late and harm has already been done
• the nuts and bolts of sth = the practical details of a subject or job
• a short heavy arrow that is fired from a crossbow
• have shot your bolt/wad = have used all of your money, power, energy etc
• make a bolt/dash/run for it = try to escape/to reach sth quickly
• bolt of lightning = lightning that appears as a white line in the sky
• a bolt from (out of) the blue = news that is sudden and unexpected
• a large long roll of cloth

1. in a nutshell, used when you are stating the main facts about something in a short, clear way
2. the ABCs of sth is the basic facts about a particular subject