Idioms/I

You can say someone's in an ivory tower if they're in a place that separates them from everyday life, such as a university.

You can say "I owe you one!" when someone has done something for you and you'd be happy to return the favour one day.

You can say "if all else fails" before saying what you'll do if your plans don't work out as well as you'd like.

You can say "if I were you" when giving advice to someone.

You can say "if push comes to shove" before saying what you'll do if things don't go as well as you'd like, and you're forced to do something that you'd rather not do.

You can say "if worst comes to worst" before saying what you'll do if your plans don't work out.

You can say "ignorance is bliss" when you want to say that not knowing about something unpleasant can be better than knowing about it and worrying about it.

If you're ill at ease, you feel tense or you can't relax in a situation.

If someone is in a bind, or in a jam, or in a fix, they're in a bad or difficult situation.

You can say "in a nutshell" if you're about to describe something as briefly as possible, or you're going to sum something up.

If something happened several times in a row, it happened several times in an unbroken sequence.

You can say "in any case" before giving an additional reason for doing or not doing something, or instead of saying "anyway".

If you're in deep water, you're in some sort of trouble or in a difficult situation.

If you're in someone's bad books, they are not pleased with you.

If you're in someone's good books, they are pleased with you.

If a person or a company is in the black, their assets are greater than their debts.

If you're in the dark about something, you don't know about it.

If you talk about something "in the long run", you mean over a long period of time.

If a person or a company is in the red, their debts are greater than their assets.

If you're in two minds about something, you can't decide what to do, or you can't decide which option is the best.

If you say it's high time something was done, you think it should have been done already, and is overdue.

If you say "it's written all over your face", you're saying that the expression on someone's face is showing their true feelings or thoughts.

If you have itchy feet, you feel the need to go somewhere different or do something different.

If something is the icing on the cake, or the frosting on the cake, it makes a good situation or a good result even better.

If you know the ins and outs of something, you know all the details about it and understand how it works.