Or is "off" simply a preposition in this case?
If it's a phrasal verb, would it still be considered so in the phrase:
Keep your hands off her.
Or is "off" simply a preposition in this case?
If it's a phrasal verb, would it still be considered so in the phrase:
Keep your hands off her.
In each case keep is the verb and off is the preposition.
In "keep off the grass" there is a contraction - the object is "implied". It's actually an imperative: "Keep everything off the grass". verb-object-preposition-noun.
In "Keep your hands off her", it's a pretty straightforwards imperative. verb-object-preposition-noun.
You can tell the 'keep off' is not a phrasal verb, because it doesn't have an idomatic meaning and because the preposition off clearly refers to a noun. This is in stark contrast to "break down" (as in "break down and cry"). In the latter case, the phrase has an idiomatic meaning, and the word "down" does not link to anything else, it is intrinsic to the phrase.
In the case of "keep off the grass", "keep" is a verb, which means "continue or cause to continue in a specified condition". The specified condition is "off the grass". Clearly off is related to the grass, and not part of a phrasal verb.
A phrasal verb is just a verb with an adverbial particle that has been 'fronted' to precede the object[s]. 'Keep off the grass' means 'keep [yourself] [to be] off {[of]} the grass.' You wouldn't change 'He kept his foot off' to *'He kept off his foot', so I don't think it is a phrasal verb. Compare that to 'He picked the can up' which can be changed to 'He picked up the can'.
Prepositions, Adverbs or both are the particles that go in the making of a phrasal verb. The phrasal verbs in turn can be transitive, intransitive or both.In the syntactic behaviour of the phrasal verb it is often seen that the object is placed before the particle or after it; and our our understanding of the phrasal verb is evidently reflected in our proper placement of the object.
KEEP YOUR HANDS OFF HER/KEEP OFF THE GRASS— In these examples objects are placed as contexts demand. It is a mere accident that in both the sentences ”KEEP" retains to some extent the meaning it conveys without the particle; but that does not rob it of its phrasal nature.
KEEP OFF: (Not talk about) She kept off the subject of her divorce.
KEEP OFF: (Not walk on) Keep off the grass.
KEEP OFF: (Keep clear of) Keep your hands off her. If we stop short of "her", still it makes sense. Two objects are present here.one of Verb another of preposition.
Hence, 'Keep off' is a phrasal verb.