"As" is a frequently used word in English and has many parts of speech including preposition, adverb and conjunction.

Here are two sentence which both have used the phrase "as...as":

1) You're as tall as your father.

2) I have as much confidence in you as in him.

It is apparent that the former "as" in both sentence is an adverb. But what's the part of speech of the latter? A preposition in sentence 1 and a conjunction in sentence 2? Does it mean the latter "as" in this phrase has no fixed function, and its part of speech depends on the context of the sentence?

And one more question: What is the part of speech of "as" in this sentence: We demonstrate that she is the murder as indicated by the knife with her blood.

Thank you!

  • Does it make more sense if you read it as: I have as much confidence in you as (I have confidence) in him? "As" preforms the same function in sentence two as it does in sentence one; it indicates an equivalent amount in both parts (I have as much X in condition one as I have X in condition two).
    – Davo
    Mar 15, 2017 at 13:10
  • @Davo Thanks. I know that. But could you answer me the question that I have added? The "as" here looks like equal to "which" but what is the part of speech here?
    – sdasd tont
    Mar 15, 2017 at 13:28
  • This has since been answered below.
    – Davo
    Mar 15, 2017 at 15:31

2 Answers 2


1) You're as tall as your father.

2) I have as much confidence in you as in him.

The first as in each sentence is indeed an adverb. The second as in each sentence is a preposition. In A student's introduction to English grammar 2005, Huddleston & Pullum write:

The second as is a preposition like than. As is used for equality, and than for inequality. (p. 200)

In most modern grammars, prepositions can take many different types of complements, for example noun phrases or clauses. For this reason we do not need to give the word as different parts of speech in examples (1) and (2).

  • +1 BUT: I think the two ases comprise a circumposition, and it's the circumposition phrase which acts as an 'adverb'. :) Mar 15, 2017 at 16:16
  • @StoneyB I'm not sure about that (scratches head). The adverb is a deictic degree adverb like so (notice you could replace the first as with so there). The preposition introduces a phrase (or clause) which acts as a semantic benchmark to tell us the extent of the degree involved. So this construction is similar to he was that big that he couldn't fit in the car, where that he couldn't fit in the car is the index for our understanding the extent indicated by the adverb that. I'm not sure whether the prep is much more than a marker here. Mar 16, 2017 at 10:01
  • It seems to me that it is the "adverb" as which is the "marker" here. He is big as a barn, but not *He is as big a barn. Mar 16, 2017 at 10:59
  • @StoneyB That kinda assuming that markers are optional - which most aren't (in spite of that). What I mean by it's markery function is that it does something similar to the words that, to and for in comparable sentences: Too big for us to ../So big that .../Too difficult to .../that big that.../As fast as... Hmm. In the other direction to your example, we have "I did it as fast I could" Mar 16, 2017 at 11:06
  • Hmm .. that's not a construction I've encountered, but that doesn't mean much. ... In any case, the point of my circumposition joke was that as...as is at bottom a construction which doesn't require or tolerate much analysis in terms of PoS. Mar 16, 2017 at 11:20

"As... as" is a conjunction in the both sentences. It is used for comparison.

  • 1
    No, actually OP is correct. The first "as" is an adverb. The second is a preposition. Both can occur independently without the other. The two words do not make up a conjunction. Mar 15, 2017 at 13:21
  • @Araucaria Thanks. And could you answer me the last question that I have added? The "as" here looks like equal to "which" but what is the part of speech here?
    – sdasd tont
    Mar 15, 2017 at 13:31
  • 2
    @sdasdtont According to H&P it is a preposition there too, but historically there are reasons for people to argue that it is a relative pronoun. I agree with H&P that in modern English it's a preposition in that example. Mar 15, 2017 at 13:35
  • @Araucaria: Thank you. Interesting, I considered "as... as" to be a correlative conjunction in the both sentences since it links words and phrases. Can you please explain me why "as" is an adverb in the first sentence? "Equally tall"? But this construction doesn't work without the second "as". And what is OP?
    – Yulia
    Mar 15, 2017 at 16:04
  • It's a deictic degree adverb. These sorts of adverb are discussed briefly in this posts here, including the word as. :-) Let me know if that doesn't help :) Mar 16, 2017 at 10:20

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