What I know

like: like + noun

like an apple.., treat like a doctor (he ISN"T a doctor)

as: as + verb


such as.., use as..., work as.., treat as a doctor (he IS a doctor), They waved as the cars passed by

What I'm dubious about:

1) He will fly as a dog 2) The table has the same height as the chair

I want to know all the rules about using 'use' vs 'like'. Because sometimes I feel that I should use 'as' with a noun but at the same time I can't elaborate (explain) this using.

Thank you in advance

  • 4
    Typically, you can't use as instead of like and viceversa as they have different roles. Mar 19, 2017 at 23:18
  • I had upvoted Lucian's comment, but what exactly does "fly as a dog" mean? Mar 20, 2017 at 9:21
  • what exactly does "fly as a dog" mean? comparison of an ability of 'dog'. The same as 'quick as Mike'
    – Max
    Mar 20, 2017 at 9:56
  • I think one sensible rule (well, I'm not very fond of rules in language learning) is that you can use them interchangeably when they mean exactly the same, e.g., Do as I do ~ Do like I do. In all other cases, they don't mean the same, so they aren't really interchangeable. Mar 20, 2017 at 12:21

1 Answer 1


I doubt you'll get "all the rules", but I'll give you at least one pointer concerning your first example.

Both "He will fly as a dog" and "He will fly like a dog" are acceptable (albeit weird, but that's OK), but idiomatically they have different meanings. The first suggests "in the role of", or "playing the part of", or perhaps "impersonating". As in:

He entered the costume party as an Imperial Stormtrooper

which suggests that he opened the door to the party, wearing his costume, and more or less politely walked in.

The second suggests "in the manner of", or "in the same way as". As in:

He entered the costume party like an Imperial Stormtrooper

which suggests he kicked in the door, and then ran into the party (possibly banging his head on the door frame while he did so), while firing a blaster, yelling, and generally creating havoc and mayhem.

Given that, "He will fly as a dog" sounds something like this. There's a bunch of people about to attempt to infiltrate the air wing of the animal invasion force. The plan is to participate in the first wave, but then to turn around and attack the next waves, so as to defeat the invasion overall. Each of us brave souls has to disguise himself as one of the various types of flying animals. John has chosen to fly as an eagle. He's awesome! Me, I'm a bit too small and hairy to pass as an eagle, but I'm going to try to pass myself off as one of the new Flying Attack Squirrels that intelligence says they're planning to use. Of course that leaves Derek, and honestly the guy is as dumb as a box of rocks. He's decided ... you'll never believe this, but I can't convince him to change his mind ... he's decided that he will fly as a dog.


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