It's generally said after someone's been hurt or scared. For example, you might say: "I tripped and fell but I'm still in one peice." It's used to mean that the person isn't hurt and is OK.
IT means something easy like the idiom piece of cake
An example for the use of the idiom 'it's a piece of cake' is: I can run that 100 yard sprint, it'll be a piece of cake'.
It emphasizes uniqueness.
"A penny" isn't an idiom - it's just a one-cent American coin.
yes
Eternal isn't an idiom. It's a word. Idioms are phrases that seem to mean one thing but mean something else.
This isn't an idiom. Telling a story means to speak and relay a tale - which can be a true one or a false one.
it means to control someone
It means to raise one eyebrow.
Obviously, to fall flat is exactly that. However, as an idiom it refers to either a joke or some piece of advice or 'wise words' that nobody properly understands. So you say these words and everybody looks at one another and says "So what?" It will have fallen flat.
This is an idiom meaning to narrow your focus down. It can also mean to narrow your aim and focus on one thing to hit. Picture the zero as a target and you get the idea of the idiom.
This is not an idiom. Some people call their loved one by a pet name like "honey" or "darling" or "sweetie."