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This is the Rachel's English 30-day challenge: Learn 30 phrasal verbs in 30 days: jumpstart your vocabulary in 2017.

Today is day 1, the first day of your 30-day challenge. We'll be studying 'crack' phrasal verbs.

Since this is day 1 of your challenge, let's start with a brief definition. What is a phrasal verb? A phrasal verb is a two-word, sometimes 3-word combination of a verb plus another word, usually an adverb, like break up, or a preposition, like sleep on: Let me sleep on it. These phrasal verbs have so many different meanings, and idiomatic meanings, figurative meanings. They're important to know because they pop up in conversation all the time.

Crack. I like this one because we have down and up. Down, up, these seem like opposites. But 'crack down' and 'crack up' are not opposites, they simply have two totally separate meanings.

'Crack down' means to be more forceful, more severe in the enforcement of a punishment, or of a rule. For example: The police are cracking down on underage drinking. Or: The university is cracking down on plagiarism.

When you put the two words together, they become a compound word, a noun. Same idea: a 'crackdown' is a severe or stern enforcement of rules, laws, or regulations. There's been a crackdown on speeding. It's also the name of a video game. Have you played it? I have not.

'Crack up' has nothing to do with rules, regulation, or enforcement. It has several different meanings.

First, it has to do with mental health. If you are not well, depressed or under pressure or anxious, and you have an event like a mental breakdown or a psychotic break, you 'crack up'. She cracked up because of the pressure of her new job. This can also be a one-word noun: He had a crackup during finals. Or, he's a crackup, he's mentally ill. Now, when you use it as a noun, "He's a crack up", it's more harsh than saying someone is mentally ill. It's kind of writing that person off. There's no sympathy for the illness when you call someone a crackup.

But it also has a meaning that's very different: when something is hilarious, very funny, and you laugh and laugh, you are cracking up. That movie cracked me up. I cracked up.

It's also used in the phrase 'cracked up to be', meaning, supposed to be, or expected. "He's cracked up to be the greatest pitcher of all time." But usually the phrase is used in the negative, when something or someone doesn't meet expectations, it's not all it's cracked up to be. Fame isn't everything it's cracked up to be.

The word 'crack' starts with the CR consonant cluster. Cr-, cr-. Your lips can form the R as you make the K sound with the back of the tongue, kr. The front part of your tongue can also be in position, pulled up and back, for the R, kr. Then all you have to do is release the back of the tongue, cr-, cra-. Then the AA vowel. Lots of jaw drop for this one. The back of the tongue lifts, the tip of the tongue stays down. AA. Cra-, crack. And another K sound at the end, back of the tongue lifts up to touch the soft palate and releases. Kk. Crack. Crack.

To review, you can crack down on something when you're serious about the rules. When you crack up, it can either mean you've had a bit of a mental break down, or the complete opposite, you've laughed really hard at something. It can also mean expected, and is usually used in the negative: making YouTube videos isn't all it's cracked up to be. It looks simple, but each video takes so much time!

To catch all of the videos in this 30-day challenge, be sure to subscribe to my YouTube channel and like Rachel's English on Facebook. Click the links in the description.

This 30-day challenge is leading up to a phrasal verbs course that will be available in my online school on February 1. Rachel's English Academy is a collection of online courses focusing on English conversation, pronunciation, and listening comprehension. You will understand Americans better, and speak better English, with these courses. Visit RachelsEnglishAcademy.com to sign up and get started today.

See the 30-day challenge playlist here and be sure to subscribe to my channel. Keep in touch with details like my online school and courses by signing up for my mailing list.