at one2 (16)WORD CHOICE: WORD CHOICE: as, like, as ifUse as in comparisons in the expression as ... as, with an adjective or adverb in between• Basketball is as popular as football here. • He can't read as well as his classmates.as is also used in the expressions not so .... as and the same (...) as• I wouldn't go so far as that. • He is the same age as me.Use likein comparisons followed by a noun• A movie is not like a book (NOT not as a book).• Like other people (NOT as other people), he values his privacy.Use as iffollowed by a clause to compare a real situation with an imaginary situation• He talked to them as if they were children.!! Some people use likein this sort of comparison• They act like they own the place. It is better not to do this as many people think it is incorrect.!!as if cannot be followed directly by a noun• You treat them as if they were your parents (NOT as if your parents).
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.