Conjunctions and Prepositions

How do you explain the difference between conjunctions and prepositions? Aren’t they both just connecting phrases? Prepositions and conjunctive adverbs especially seem almost the same.

In these sentences, what are “before” and “after”?

Before answering this question, consider the consequences.

The pitcher will be ready to go after resting a few days.

To allow a BASIC UNDERSTANDING to form further learning … use this theory …

The preposition can be thought of as giving the position of an action relative to another.
The conjunction gives the affect, reason, requirement and more … of one action upon another.

e.g.

The pitcher will be ready to go after resting a few days.
(action 1 “ready to go” comes after action 2 “resting”) … Position

The pitcher will be ready to go, but he must first rest a few days.
(action 2 “resting” is a requirement for action 2 “ready to go”) … Requirement

another example …
We will give him the letter upon his arrival. ---- Position

Maybe not the official theory, but I have found that students seem to be able to develop from this explanation.

SIMPLE ! (ish)

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Both before and after are prepositions, with the -ing verb form serving as a noun object. Conjunctions take a following finite or non-finite clause:

Before you answer the question, consider…
The pitcher will be ready after he has rested…
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