How to Use "As" as a Preposition

The humble word "as" may appear small, but it packs a punch when it comes to expressing a range of ideas in English. While it often functions as a conjunction, "as" also plays a crucial role as a preposition.  As a preposition, "as" connects a noun to another word or phrase, often indicating the person's role, function, capacity, or manner of doing something.

In the Ngram graph below you can see that "as" has been used fairly consistently from the 1800s to the 2000s, with its use dipping slightly in the 1990s, but then increasing back to its normal levels by the latter 2000s.

How to use "as" as a preposition?

Expressing Roles and Functions

The most common use of "as" as a preposition is to denote someone's role or function. We use it to introduce someone in a particular capacity.

• "She works as a doctor."
• "He was chosen as the team captain."

By using "as," we clearly establish a person's position within a context, making the relationship between them and the rest of the sentence readily apparent.

Indicating Capacity or Purpose

"As" also helps us express the capacity or purpose of something. For example:

• "The room can be used as a study."
• "This can be worn as a scarf or a headband."

In these instances, "as" identifies the intended use or function of an object, clarifying its significance and purpose.

Denoting Time, Manner, or Condition

"As" can also signal specific conditions, manners, or timeframes. Here are some examples:

• "As the sun set, the sky turned a fiery orange." (Time)
• "He did as he was told." (Manner)
• "As she spoke, the room fell silent." (Condition)

In these cases, "as" introduces a circumstance or attribute that modifies the main clause, adding detail and context to our writing.

Making Comparisons

"As" plays a crucial role in forming comparisons, allowing us to connect two entities or ideas. We use it to establish similarities and differences, as in:

• "She is as tall as a tree."
• "He is not as clever as he seems."
• "As you can see, the results are clear."

Here, "as" acts as a bridge between two elements, drawing our attention to their relationship and highlighting their relative qualities.

Helpful tips when using "as" as a preposition

While "as" is a versatile preposition, its usage requires careful consideration to avoid confusion and ambiguity. Here are some helpful tips to guide you:

Identify the function

• Introducing roles or functions: Use "as" to denote someone's capacity or position, like "He works as a lawyer" or "She was chosen as the captain."
• Indicating capacity or purpose: Use "as" to describe the intended use of something, like "This can be worn as a scarf" or "The book serves as a guide."
• Denoting time, manner, or condition: Use "as" to signal circumstances or attributes that modify the main clause, like "The sun set as they walked" or "He did as instructed."
• Making comparisons: Use "as" to draw parallels between two entities, like "She is as tall as a tree" or "The results are as expected."

Choose the correct preposition

While "as" covers various roles, other prepositions might be more precise in certain situations. For instance, instead of "He walked in as to the room," consider "He walked into the room."

Avoid double prepositions

Double prepositions are generally grammatically incorrect. Avoid phrases like "He looked as he was lost" or "She sat beside as me."

Ensure clear subject-verb agreement

When "as" introduces a clause, make sure the subject and verb within the clause agree in number. For example, "He played as he wanted" is correct, while "He played as she wanted" is not.

Use commas strategically

For non-restrictive clauses introduced by "as," use commas to set them apart. For example, "He spoke calmly, as he always did." Restrictive clauses don't need commas: "The book as I read it was fascinating."

Avoid overuse in comparisons

Excessive use of "as" in comparisons can be repetitive. Consider alternatives like "similar to" or "in comparison to" for variety.

Now that you've learnt the ins and outs of "as" as a preposition. Let's put your learning into practice.

Answer Key

Exercise 1: Identifying the Function of "As"

1. Introducing a role or function
2. Indicating capacity or purpose
3. Denoting time
4. Making a comparison
5. Denoting manner

Exercise 2: Rewrite the Sentences

1. He smiled, feeling happy as he could be.
2. She walked down the street, lost in thought as she often did.
3. They finished their work, exhausted but satisfied as they always were.
4. The children played in the park, laughing and shouting as children often do.
5. The sun set, casting long shadows across the landscape as it does every day.

Exercise 3: Sentence Correction

1. He walked into the room.
2. She is as clever as her sister is.
3. He looked as if he were lost.
4. I did the same thing as you did.
5. They sat beside me.
   

Want to sound like a native speaker?

Engram’s AI-powered grammar checker makes your English sound like a native speaker’s, suggesting natural English expressions on top of fixing grammar, spelling, punctuation, word order, and vocabulary.

Free ChatGPT-Powered Grammar Checker | Engram

Use Engram’s free grammar checker, powered by ChatGPT, to fix your grammar, spelling, punctuation, and word usage errors

Engram

References:

Definition of AS

to the same degree or amount; for instance : such as; when considered in a specified form or relation —usually used before a preposition or a participle… See the full definition

Merriam-Webster Logo