A phrasal verb consists of a verb and a preposition or adverb that modifies or changes the meaning ;

'give up' is a phrasal verb that means 'stop doing' something, which is very different from 'give'. The word or words that modify a verb called particle. They are widely used in both written and spoken English, and new ones are formed all the time as they are a flexible way of creating new terms.

Examples :

act up (no object): misbehave (for people); not work properly (for machines).

"The babysitter had a difficult time. The children acted up all evening.“

"I guess I'd better take my car to the garage. It's been acting up lately."

act like (inseparable): behave in a way that's like _____ . "What's wrong with Bob? He's acting like an idiot."

Note: This phrasal verb is very informal.

"His theory seems, at first, to be plausible, but the facts in his research don't add up."

add up (2. separable): find the total.

"What's the total of those bills? Could you add them up and see?“

add up to (inseparable): to total.

"The bills add up to $734.96. That's more than I expected!"

An idiom is a group of words with the meaning of the individual words are different from the meaning of the whole phrase.Examples:

bad-mouth: say unkind, unflattering, embarrassing (and probably untrue) things about someone.

A: "I don't believe what Bob said. Why is he bad-mouthing me?“

B: "He's probably jealous of your success."

be a piece of cake: be very easy.A: "Bob said the test was difficult, but I thought it was a piece of cake.“

be all ears: be eager to hear what someone has to say.

A: "I just got an e-mail message from our old friend Sally."B: "Tell me what she said. I'm all ears!"