The word "while"

A conjunction joins two (or more) things together. There are not 2 things in your examples, so these words cannot be determined to join 2 things together. More context is needed.

Examples
1) We watched TV while having lunch. - "while" is a preposition.
2) We studied Latin while we were in school. - while is a conjunction (joining a subordinate to a main clause)
3) Before eati

Anonymouswhile having lunch

while in school
before eating lunch

I would call while and before conjunctions. The following clause is highly reduced, but in each case a clause is implied. Its exact contents depend on the context. Those with -ing are participial constructions. A form of the linking v

Hi. Thank you. Could you please tell us how we could convince ourselves of the fact that these have clauses that are implied?

while having lunch

before eating lunch

AnonymousHi. Thank you. Could you please tell us how we could convince ourselves of the fact that these have clauses that are implied?

while having lunch

before eating lunch

Someone had to be having lunch! That's the implied subject of the clause. You don't know that subject until you see the whole sentence because the subject

Hi. Thank you for your help.