Question

Help me can you tell me where to use" as" and where to use" like"? Thanx!

Answer 1

From http://learnenglish.britishcouncil.org/en/grammar-reference/and

AS

• to talk about job or function (I worked as a shop assistant. He used his shoe as a hammer.)

• ‘as adjective as’ (He’s not as tall as his brother. She ran as fast as she could.)

• as a "and" between two sentences (He went to Cambridge University, as his father had before him. She’s a talented writer, as most of her family are.)

• as if

  You look as if you’ve seen a ghost.

• as though

  You talk as though we’re never going to see each other again.

• in sentences:
  

"as you know"

"as you suggested"

"as we agreed"

"as mine." /yours/his/hers/ours/theirs.

LIKE

• followed by a noun or a pronoun.

I’ve been working like a dog all afternoon.

None of my brothers are much like me.

She looks just like her mother.

• between two clauses with a subject and a verb.

  It looks like it’s going to rain.

Answer 2

like is a preposition so we need to put it before a noun or a pronoun. (You're like a child!)

as is a linking word/conjunction and we put it before a clause (She's scared, as we all are.)

although, in general english, we can use like as a linking word, too. (She doesn't dress like you do.)