I am confusing about which one is correct

  1. Mark wrote too slow on the exam. He always writes slowly.

  2. Mark wrote too slowly on the exam. He always writes slowly.

Do anyone have an idea about which one is correct.

  • You might also ask "too fast / to fastly".
    – Ahmed
    Commented Nov 29, 2018 at 15:48
  • You are too slow. You are moving too slowly.
    – Hot Licks
    Commented Nov 29, 2018 at 17:09

3 Answers 3


The answers reflect the diversity of thought on this, however @eenbeetje answer is correct. Both can be used, but "slowly" is, shall we say, less controversial because it is the conventional form of the adverb. But the link is @eenbeetje answer is an excellent one to learn about flat adverbs. As I commented there, they are considerably more common in the US than in Britain.

However, I did want to point out a great example of this, and that is that famous Apple slogan of "Think Different". I think it is one of the greatest slogans of all time because it is this self referential thing. You read it and think: "Hey, shouldn't that be 'think differently'" then you realize that people do say "think different', and it is a bit off, a bit unconventional, a bit edgy (and, also correct.) The wording itself, and how you react to it conveys exactly the ideas that Apple wanted to convey to you about their products. "Different", "edgy", "coloring outside the lines", "the regular folks think it is wrong, but they just aren't smart enough to know that it is in fact correct."

How you can convey all that feeling and reaction in just two words is quite remarkable. Whoever wrote it is a genius.

  • You should answer more careful. Flat adverbs aren't always available. Commented Feb 28, 2020 at 12:40

Both are correct, but "slowly" is generally considered the more formal and proper version.

When the adjectival form of the word is used as an adverb, it is called a flat adverb, and there is nothing per se incorrect about the usage. In fact there are some adjective-adverb pairs in English that, as this MacMillan blog points out, don't have -ly counterparts at all, like "long" and "fast." The issue arises with prescriptivist rules from the 18th Century that were largely unfounded as discussed by Emily Brewster of MerriamWebster in this video.

  • 1
    FWIW, based on my experience living in both countries, Americans tend to use flat adverbs considerably more often than the British do. Having said that, although the answer is correct, and Emily Brewster is also correct, the plain fact is that for a learner of English I would recommend avoiding flat adverbs when a -ly adverb is available. Not because it is wrong but simply it will sound wrong, and sound poor grammar in the ears of many people. So, IMHO it is better to avoid the controversy. Better to make your language smooth in the ear of the hearer.
    – Fraser Orr
    Commented Nov 29, 2018 at 16:44

The second sentence is grammatically more correct because there is an adverb /slowly/ modifying the verb. 'Slow' is an adjective which modifies nouns. So the first sentence is not grammatically correct. But according to Etymology Online Dictionary, since the 15th century 'slow' has been both an adjective and adverb. These homonyms are marked in all English Dictionaries. But 'slowly' is used as well. So in many cases there is no difference between 'slow' and 'slowly', for example: to work/drive slow/slowly. To my mind, according to a current tendency, 'slow' seems more informal than 'slowly'.

  • This answer requires more context. Road signs that say "Drive slow" are seen everywhere and (mostly) considered acceptable. Commented Nov 29, 2018 at 15:12
  • @JasonBassford Road signs also say "PED XING". Commented Nov 29, 2018 at 17:30

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