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Is "before" in the following sentemce a conjunction or a preposition.

Please come before the meeting starts.

(Although it has the object the meeting but still it's confusing)

In a prepositional phrase, can a verb follow the object of the preposition?

GB
Comments  
You should always wash your hands before meals.

"(B)efore meals" is an adverb phrase, but before is not an adverb because it has an object to complete its meaning.
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Before leaving he said good-bye to me.
'Before' here is not a preposition because there is no object that links to the clause of which it is a part.
Before is followed by a subordinate clause; therefore, it is a sub. conj.
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He said he had never seen her before.

An adverb indicates time.
'(B)efore' here means in the past; therefore, it is an adverb.
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Please come before the meeting starts.

Before the meating comes, please come.

The meeting comes
please come
they are two clauses
please come is more important than when you should come.
Therefore, please come is the main clause.
The other plays a subordinate role.
The clauses are linked by a subordinate conjunction: before.
(If the clauses were equally important, than they would be linked by a coordinator.)

Does it help you?
InchoateknowledgePlease come before the meeting starts.

Before the meating comes, please come.

The meeting comes
please come
they are two clauses
please come is more important than when you should come.
Therefore, please come is the main clause.
The other plays a subordinate role.
The clauses are linked by a subordinate conjunction: before.
(If the clauses were equally important, than they would be linked by a coordinator.)

Does it help you?
Well ... the explanation was quite good but can you explain how "please come" is a clause - I mean a clause must have a subject and a verb. "Please come" has a verb but where is the subject (or the subject is elliptical).

GB
Teachers: We supply a list of EFL job vacancies
Please, come.
You have got me there.
Ellipsis? maybe.
Does imperative sentences constitute a grammatical sentence?
Go! Is it a sentence?
(sentence means clause here to me.)
All imperatives have an implied subject "you".
Go! is a complete sentence, yes. The subject is "you".

CJ
Thanks Jim.
Students: We have free audio pronunciation exercises.
It is a subordinating conjunction. The key is to check for subject and verb following the conjunction. If so, it is a conjunction connecting a subordinating clause, if not it is a preposition.