The rule, as people use it
An adjective describes a thing. An adverb describes an action: how you do it, when, or how often. Most adverbs of "how" are the adjective plus -ly: slow, slowly; quiet, quietly; careful, carefully. "She's a careful driver" describes her. "She drives carefully" describes the driving.
The one that trips everyone is good and well. "Good" describes a thing: "a good cook", "the food is good". "Well" describes the doing: "He cooks well." So "You speak English very good" is the slip, and "You speak English very well" is the fix. A few more words keep the same form in both jobs: fast, hard, late, early. "He works hard" is right. "He works hardly" means almost nothing, which is a very different message.
Adverbs of how often, like always, usually, often, sometimes and never, go before the main verb but after "be": "I usually walk to work." "She's always late." Words that make an adjective stronger or softer, like very, really, pretty and a bit, go right before it: "really tired", "pretty good".
Examples
Tap a sentence to hear it. Say it after the voice.
Fill the gap
Type the missing words, then check. The full sentence plays when you get it.
- 1
Please close the door (quiet). The baby is asleep.
- 2
Yuki sings really (good / well).
- 3
Harry is a very (careful / carefully) driver.
- 4
Mateo works (hard / hardly) every day.
- 5
We (always) have pizza on Fridays.
- 6
The bus was (late / lately) this morning.
- 7
I can't hear you. Can you speak more (clear)?
- 8
Your English is really (good / well).
Practice · 3 min
Write six sentences about your week. Use one -ly adverb, one sentence with "well", one with "hard" or "fast", and three with how often: always, sometimes and never. Say each one out loud. Then check two things: the how-often word comes before the main verb, and nothing you do is described as "good" when you mean "well".
Say it today
Use it once in a real conversation before tomorrow. Out loud counts, even to yourself.