The BBC’s Matthew Anderson tweeted about a rule that “English speakers know, but don’t know we know.” It was a screen grab of a passage from Mark Forsyth’s The Elements of Eloquence explaining that the reason “great green dragons” sounds better than “green great dragons” is that we unconsciously follow a rule that stipulates that the order of adjectives in English goes opinion-size-age-shape-color-origin-material-purpose. Size comes before color, so no “green great dragons.”

People reacted to the tweet with amazement, astonishment, and thousands of retweets. It can be shocking to realize that we are able to follow rules that no one ever taught us explicitly. But that’s what most of language is: Not the little things that textbooks tell us we’re getting wrong, but the solid ones we always get right. Non-native speakers, however, might get them wrong, and that gives us a good opportunity to get a peek at the rules we don’t otherwise notice.

1. WHY “MY BROTHER’S CAR” AND NOT “THE CAR OF MY BROTHER”

There are two main ways to express possession in English, one with possession marked on the possessor (my brother’s car) and one with an “of” phrase (the car of my brother). Teachers and usage guides don’t usually give rules telling you why “the car of my brother” sounds bad but “the door of my house” sounds fine, because no one thinks to say “the car of my brother” in the first place. But why not? After all, languages like Spanish and French use this kind of construction (el coche de mi hermano, la voiture de mon frère). Why does “my brother’s car” sound so much better than “the car of my brother,” but “my house’s door” sounds the same or worse than “the door of my house”?

We don’t know it, but we make these phrases with reference to something called the animacy hierarchy. The hierarchy in this case is basically a scale in decreasing order of humanness going from human to animal to inanimate objects. The higher in animacy the possessor is, the worse the “of” phrase type of construction sounds. So,

"my brother's car" sounds better than "the car of my brother"

"my parakeet's cage" sounds a bit better than "the cage of my parakeet"

"my house's door" sounds the same or worse than "the door of my house"

Of course, there are considerations like conversational context and rhetorical effect that result in exceptions to this rule, but it does account for a lot of the difference in the relative acceptability of these two syntactic choices. For example, “city hall” can be conceived of as an inanimate building ("the steps of city hall") or a collection of people ("city hall’s announcement").

2. WHY ABSO-FREAKIN’-LUTELY AND NOT ABSOLUTE-FREAKIN’-LY

There’s a way to emphasize a word in English that involves inserting an expletive into the middle of the word—but not just anywhere in the middle. While abso-freakin’-lutely sounds right, ab-freakin’-solutely and absolute-freakin’-ly sound terrible. There is a rule at work here, having to do with the syllable structure of the word. Essentially, you find the syllable with the most emphasis inside the word and put the swear word before it. Kalama-freakin’-ZOO. Im-bloody-PORtant, la-freakin’-SAgna.

Things get tricky when the only stress is on the first syllable (YESter-freakin’-day? Ele-bloody-phant?) or when there are other, more separable boundaries in the word like un- or re- (un-freakin’-beLIEVable and re-freakin’-poSSESSED, are better than unbe-freakin’-LIEVable and repo-freakin’-SSESSED), but these exceptions can be categorized and explained. The important thing is that there’s a rule, and we already know how to apply it, even if we can’t state it.

3. WHY “WHAT DID YOU SAY THAT HE ATE?” AND NOT “WHAT DID YOU MUMBLE THAT HE ATE?”

In English, when we ask a who/what/where/when/why question, there is usually a slot in the sentence where the answer would fit if it were not a question. For “What did you eat?” the corresponding sentence is “I ate __ [potatoes/an apple/my breakfast…].” For “Where did they go?” the corresponding sentence is “They went __ [to the beach/to lunch/downstairs…].”

Linguists talk about these types of questions in terms of movement; it’s as if the 'wh' word has moved from the non-question sentence slot to the beginning of the sentence. Wh-movement can also happen out of phrases a long way from the beginning of the sentence. “What did you say that the beginning of the movie reminded you of?” corresponds to “You said that the beginning of the movie reminded you of __ [moving day/the weather report/ancient Greece…].”

But there are many cases where you can’t do this kind of movement. For example, for these complex, long distance cases, the main verb of the sentence must belong to a specific class of verbs linguists call bridge verbs. Say is a bridge verb (“What did you say that he ate _____?”) but verbs that include the manner in which something was said (mumble, shout, whisper, sob) are not. So “What did you mumble that he ate ___?” sounds terrible. We don’t make those kinds of sentences because we know the rule, even if we don’t know there is a rule.

4. WHY “I CHEERED UP MY FRIEND” AND NOT “I CHEERED UP HER”

English has a group of verbs known as phrasal verbs that give language learners a major headache. These are verbs made of multiple words that together give a different meaning than you would expect by simple combination. For example blow up is a phrasal verb because it means “explode” not “blow in an upward direction.” You just have to learn what these mean. They are verbs like call off (cancel), go over (review), and put down (insult). There are hundreds of them.

Phrasal verbs do not all work according to the same rules. Some do not allow an object to come between the parts of the verb: You can say “Don't pick on your sister” but not “Don't pick your sister on.” But other phrasal verbs can be separated: You can say “Let’s call off the meeting” or “Let’s call the meeting off.” Native speakers know which ones are separable and which are not without ever looking at a rule book. Non-native speakers have to learn the difference through painstaking experience.

But that’s not all. Even the separable verbs have a restriction on them that native speakers never explicitly learn about. Cheer up is separable. You can say “I cheered my friend up” or “I cheered up my friend.”  But if you want to substitute my friend with a pronoun, it must be placed between the parts of the verb. You cannot say “I cheered up her” only “I cheered her up.” For the inseparable verbs, pronouns are no problem: "Don't pick on her."

In the rest of English grammar you can substitute a pronoun anywhere you have a noun phrase. Not in this case. But you already knew that, even if you didn't know you knew that.