Overview
Like is a preposition meaning 'similar to' and is followed by a noun or pronoun (She sings like a professional). As is a conjunction meaning 'in the same way that' and introduces a clause (Do as I say), or a preposition meaning 'in the role of' (She works as a teacher). Confusing like and as is a very common error.
Like — Preposition (Similar To)
- RuleLike + noun/pronoun — means 'similar to'
- ExampleShe sings like a professional.
- ExampleHe looks like his father.
- WrongShe sings like she is a professional is informal — use as if in formal English
As — Conjunction or Role
- ConjunctionAs + subject + verb: Do as I say.
- RoleAs + noun = in the role of: She works as a doctor.
- ComparisonAs…as: She is as tall as her brother.
- NoteAs if / as though + clause: He acts as if he owns the place.
Common Errors
- WrongShe works like a teacher → implies she's not really a teacher
- RightShe works as a teacher → she IS a teacher (role)
- ClauseAs + clause (subject + verb): He did as she asked.
- NounLike + noun (no verb): He ran like the wind.
When to use
Like (similar to)
He sings like a professional.
As (role)
She worked as a nurse for ten years.
As (conjunction)
Do as the instructions say.
As if
He spoke as if he knew everything.