Using English correctly requires a massive amount of knowledge

Why is it so difficult to learn a language? The main reason is that speaking a language correctly requires a vast amount of knowledge – far greater than is necessary to be a competent doctor or lawyer. A large chunk of this knowledge is, of course, vocabulary. To speak English fluently, you have to know the meanings and pronunciations of at least 10,000 words and phrases (for comparison, the average college student in the US knows about 20,000 words).

But while most learners realize vocabulary is a major area that requires a lot of attention, fewer are aware that there is an equally large body of facts that is described with the word usage. Usage is a very general term that refers to using words, phrases and grammar structures in the right situations, and joining words together to form correct sentences. For example, the fact that extremely means “very much” is a matter of vocabulary; the fact that you cannot say Mary extremely likes cheese is a matter of usage.

Usage is not the same thing as grammar. Grammar, as it is typically understood by teachers and learners, consists of “big”, general rules which apply to grammatical structures and important “grammar words” like prepositions, conjunctions and pronouns – for example:

• When have is used as a regular verb, we do not contract it to ’ve: I’ve a question.
• In a since-clause that refers to a point in time, we use the simple past tense: I’ve lost 20 pounds since I started exercising.
• We do not use the present perfect tense when we’re thinking of a finished period: I’ve been there yesterday.
• Despite takes a noun or something that acts like a noun, so we can say despite their defeat or despite the fact that they lost, but not despite (that) they lost.
• We use through when one thing is surrounded by another (to put a stake through a vampire’s heart) and across when one thing is on another (to draw a line across the page).
• Everybody, everyone, anybody, anyone, nobody and no one are singular, so we say Everybody makes mistakes, not Everybody make mistakes.

Such general rules constitute only a small percentage of usage. Most of “usage” is thousands of little facts that apply only to a specific word or combination of words:

• collocations (which words go together):
  • last hope but final decision
  • completely different but fully aware
  • electric motor but electrical components
  • fast car but quick look
  • heated debate but burning issue
  • heavy smoker but bad/terrible headache
  • strong medicine but severe pain
  • clean your teeth but wash the dishes
  • make a plan / a phone call / money / a mistake / a jump
  • do an experiment / business / an exercise / the laundry
  • have a conversation / an effect / breakfast / a party
  • take a photo / a step / an exam / a risk / a note
  • deal a blow, strike a balance, pose a threat, stand a chance, hold a belief, give way
• register (formal vs. informal words and grammar structures):
  • Don’t be sullen sore. (sullen is formal)
  • Where the hell are they? I hope nothing bad transpired happened. (transpire is formal)
  • “Where’s the remote?” “Atop On the sofa.” (atop is formal and old-fashioned)
  • The discrepancy between our results and those published in DeKeyser [13] did not appear to be a big deal important. (big deal is informal)
  • A statistical approach was taken because a manual review of all the reports was not deemed doable feasible. (doable is informal)
• connotations (emotional overtones of words):
  • He’s a true friend but not He’s a true asshole (true is positive – clashes with asshole)
  • Do you guys sell hardware? I need some bolts. but not Do you guys peddle hardware? (peddle is disapproving)
  • The room was small and simple but not The room was little and simple (little is emotionally charged)
  • It was just a stupid little joke but not It was just a stupid small joke (small is emotionally neutral)
• where words can go:
  • Even Carl agreed we should sell now but not Also Carl agreed we should sell now
  • I did what I could but not I asked who I could
  • We drove to the nearest gas station but not We drove to a near gas station
  • This is the only reason but not This reason is the only / Screw that damn house but not That house is so damn / She’s a hard worker but not Our workers are hard
  • Our daughter is ill but not their ill daughter / Only four students were present but not the four present students / What went wrong? but not They wrong accused him
• what words, phrases and structures are used in particular situations:
  • What size is it? but not What weight is it?
  • “The phone is ringing!” “I’ll get it!” not “I’ll take it!”
  • (handing somebody the phone) “It’s for you.” not “It’s to you.”
  • Here, have a cookie not Here, eat a cookie
  • He broke his foot but He shot himself in his the foot
  • He has a headache but He has is having a heart attack
• what structures go with what words:
  • They asked me to leave but They suggested me to leave that I leave
  • The teacher told me the answer but The teacher explained me the concept the concept to me
  • We encourage our kids to read but We discourage our kids to play videogames from playing videogames
  • I’m undecided but not I’m decided
  • The game is finished but not The game is started
• which verbs need an object (may also depend on the meaning and context):
  • I love to build but not I love to fix
  • When I finish college, I’d like to teach but not I tried to learn cooking from my father, but he didn't want to teach (depends on the exact meaning)
  • If you want to accomplish anything, you have to believe but not They told me he was cheating on me, but I didn’t believe (depends on the context)
• what prepositions go with what verbs (may also depend on the grammatical and situational context):
  • talk about something but comment on something but discuss something
  • succeed in something but fail at something
  • ask a question of somebody but have a question for somebody
  • accuse somebody of something but blame somebody for something
  • answer an e-mail but reply to an e-mail
  • I invited her to the party but I invited her for a drink (depends on the object)
  • I left Portland in a hurry but The train leaves from Central Station (depends on the emphasis)
  • The bank approved my loan but My parents didn’t approve of my plan (depends on the exact meaning)
• what prepositions go with what nouns and adjectives (may also depend on the meaning):
  • At the time, we still lived on Thornhill Place.
  • Who’s the person in the picture?
  • I thought she was on drugs.
  • We have seen a tremendous increase in crime.
  • The radio was playing a song by David Bowie.
  • I was impressed with their work.
  • I’m surprised at you.
  • I’m tired of your whining but We were tired from the climb (depends on the exact meaning)
  • The phone is made of aluminum but Our mayonnaise is made from organic eggs (depends on the exact meaning)
• which nouns are countable (may also depend on the meaning and context):
  • That’s a very unusual opinion but not That’s a very unusual advice
  • I didn’t have enough money for a cake but not I didn’t have enough money for a bread
  • He built every cabinet in his house but not He built every furniture in his house
  • Let me give you one more fact but not Let me give you one more information
  • A cantaloupe is a fruit but not Would you like a fruit? (depending on the exact meaning)
  • My computer is crap but not I don’t give crap (depending on the context)
• which determiners (including articles) go with which words (may depend on the context):
  • Politicians are disconnected from the world but Politicians are disconnected from the reality
  • I’ve got a cold but I’ve got a the flu
  • I married a bad guy but I married a the wrong guy
  • It’s written in small print but It’s written in a small font
  • I have to be in the office until 7 pm but I have to be at the my desk until 7 pm
  • Judge Hayworth is in the office right now but Judge Hayworth has been in the office for 20 years (depending on the exact meaning)