Prepositions are relationship words. They provide clues and link the remainder of the sentence together. Given their important role, there are several important rules for prepositions to remember.

These rules relate to how they can be used, which prepositions can be used when, and where they belong in the sentence. Let's dive right in.

Preposition Rules

Did you know there are hundreds of prepositions in the English language? A fun way to remember prepositions is that they are words that tell you everywhere a bunny can run; for example, a bunny can run:

up
down
near
far
by
at
around
close
always

With some of these popular prepositions in mind, let's look at six important rules for prepositions.

1. Pair Them Properly

Determining which preposition to use can be a tricky proposition. It's especially difficult when dealing with idioms - expressions in the English language that don't necessarily make sense when taken literally.

Idiomatic expressions are expressions you just have to memorize, and when errors are made, they're almost always prepositional errors. Here are some examples of idioms, along with the correct prepositions:

George will be able to attend the party.
You're capable of anything you set your mind to.
Shelly's been preoccupied with work lately.
The teacher is concerned by Janette's consistent tardiness.
Employees are prohibited from smoking on company property.

Each of the prepositions in bold are the only acceptable prepositions to follow the verbs that precede them. For example, it wouldn't be grammatically correct to say "able with" or "capable to." For more, enjoy Idioms That Begin with Prepositions.

2. Watch What Follows Them

Prepositions must always be followed by a noun or pronoun. That noun is called the object of the preposition. Note that a verb can't be the object of a preposition. Let's look at two examples:

The bone was for the dog.
This is correct. The preposition for is followed by the noun "dog."
The bone was for walked.
This is not correct. The preposition for is followed by a verb "walked." Walked can never be the object of a preposition.

This rule may seem confusing at first; you may have seen words that look like verbs following the preposition to. For example:

I like to ski.
These boots are for skiing.

However, in these examples, "ski" and "skiing" are not acting as verbs.

In the first example, to ski is part of the infinitive. An infinitive occurs when a verb is used as a noun, adjective, or adverb. Here, to ski is a thing that the person likes doing, not an action they are performing.
In the second example, skiing is a gerund. Although a gerund is created out of a verb, it's actually a noun. Here, skiing is a thing that the boots are for. No one in this sentence is performing the act of skiing.

3. Avoid Using Them at the End of Sentences

Because prepositions must be followed by a noun and have an object, they should rarely be placed at the end of a sentence. For example, it's generally not correct to say:

The table is where I put my books on.

However, there are certain circumstances where it is acceptable to end a sentence with a preposition. These exceptions exist where the preposition isn't extraneous. In other words, the preposition needs to be there, and if it wasn't, the meaning of the sentence would change.

In the above example, the use of the preposition "on" isn't necessary. We could remove "on" and the meaning would be the same. Therefore, the preposition was extraneous or unnecessary.

That said, here's an example where it's perfectly acceptable to use a preposition at the end of a sentence:

I turned the TV on.

If you removed "on" from the end of this sentence, it would change the meaning. Instead of switching on the set, you would be saying that you turned the TV itself. Alternatively, this could be written as, "I turned on the TV."

4. Never Substitute "Have" for "Of"

Teachers, writers, and grammarians would cringe at this construct:

I should of come over.

Eek. Although it sounds like we say this all the time; we don't really. We might say, "I should've come over," but that's about it. Here's what the above sentence should look like:

I should have come over.

"Have" is an important helping verb. The preposition "of" does nothing here to link or join ideas together, as every preposition should.

5. Don't Confuse "In" and "Into"

When you want to express motion toward something, use "into" rather than "in." Reserve "in" for moments when you want to indicate a location. Here are some examples:

I swam in the lake. (Indicating location)
I walked into the pub. (Expressing motion)
Look in the cupboard. (Indicating location)
She drove into the city. (Expressing motion)

6. Try Not to Interchange "Than" and "From"

We'll close with more of a suggestion than a hard and fast rule. It deals with the word "different." Try to avoid this:

You look different than your mother.

Instead, opt for:

You look different from your mother.

While the first example isn't wrong, per se, a bonafide grammarian would scoff at the pairing. Why not go for the surefire win over the potentially eyebrow-raising format?

Peaceful Prepositions

Sometimes, it seems like prepositions are the peacemakers of the English language. They join it all together with cohesion and clarity. They maintain a thought's fluidity. For more on these peacemakers, check out these preposition games and preposition worksheets.

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"Rules for Prepositions." YourDictionary, n.d. Web. 23 January 2019. <https://grammar.yourdictionary.com/parts-of-speech/prepositions/rules-for-prepositions.html>.

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Rules for Prepositions. (n.d.). Retrieved January 23rd, 2019, from https://grammar.yourdictionary.com/parts-of-speech/prepositions/rules-for-prepositions.html