i just want to ask what are the uses of AS as a preposition?

Question

as a punishement? what is the use of as here?

Answer 1

"As" is a preposition when it can be replaced with "like"
and mean the same thing.
* "as" a punishment
OR
* "like" a punishment
Mean the same thing; both
"as" and "like" are "prepositions" here.

Other phrases that use "as" in preposition form:
as (can also be a subordinating conjunction) .
as of
as to
as + ADVERB OF TIME + as
as early as
as late as
as often as
as much as
as many as, etc.

When "as" is NOT a preposition but a subordinating conjunction,
There is a separate subject and verb in the clause:
... "as" I went out the door.

See more examples from American Heritage Dictionary:

as 1 (z; z when unstressed) KEY

ADVERB:

To the same extent or degree; equally:
* The child sang as sweetly as a nightingale.
* For instance: large carnivores, as the bear or lion.
When taken into consideration in a specified relation or form: this definition as distinguished from the second one.

CONJUNCTION:

To the same degree or quantity that. Often used as a correlative after so or as:

* You are as sweet as sugar.
* The situation is not so bad as you suggest.
In the same manner or way that:
* Think as I think.
At the same time that; while:
* slipped on the ice as I ran home.
For the reason that; because:
* went to bed early, as I was exhausted.
With the result that:
* He was so foolish as to lie.
Though:
* Great as the author was, he proved a bad model.
* Ridiculous as it seems, the tale is true.
In accordance with which or with the way in which:
* The hotel is quite comfortable as such establishments go.
* The sun is hot, as everyone knows.
Informal That:
* I don't know as I can answer your question.

PRONOUN:

That; which; who. Used after same or such:
* I received the same grade as you did.
Chiefly Upper Southern U.S. Who, whom, which, or that:
* Those as want to can come with me.

PREPOSITION:

In the role, capacity, or function of:
* acting as a mediator.
In a manner similar to; the same as:
* On this issue they thought as one.

Answer 2

You just used the word 'as' in your question.
.