Common Mistake: Comma before 'so/but/and'

One common mistake in English grammar is the incorrect use or omission of a comma before the words 'so', 'but', and 'and'.

When to use a comma before 'so'

Generally, a comma should not be used before 'so'. However, there are cases when a comma is needed.

• Use a comma before 'so' if it connects two independent clauses:

Incorrect: I finished my work so, I decided to go for a walk.

Correct: I finished my work, so I decided to go for a walk.

In the correct example, a comma is necessary because it separates two independent clauses: "I finished my work" and "I decided to go for a walk."

Keep in mind that if the two clauses are closely connected and short, a comma may not be needed:

Incorrect: I finished my work so I decided to go for a walk.

Correct: I finished my work so I decided to go for a walk.

In this example, the two clauses are closely connected and short, so a comma is not necessary.

When to use a comma before 'but'

Similarly to 'so', a comma is not typically used before 'but'. However, there are instances when a comma is required.

• Use a comma before 'but' if it connects two independent clauses:

Incorrect: I wanted to go to the store but I was too tired.

Correct: I wanted to go to the store, but I was too tired.

Again, the comma is necessary to separate the two independent clauses: "I wanted to go to the store" and "I was too tired."

If the clauses are closely connected and short, a comma may not be necessary:

Incorrect: I wanted to go to the store but I was too tired.

Correct: I wanted to go to the store but I was too tired.

In this example, the clauses are closely connected and short, so a comma is not needed.

When to use a comma before 'and'

The use of a comma before 'and' depends on the context and the structure of the sentence.

• Use a comma before 'and' if it connects two independent clauses:

Incorrect: I went to the store and I bought some groceries.

Correct: I went to the store, and I bought some groceries.

Once again, the comma is necessary to separate the two independent clauses: "I went to the store" and "I bought some groceries."

However, if the 'and' joins two words or phrases within a sentence, a comma is not usually required:

Incorrect: She wore a red, and yellow dress to the party.

Correct: She wore a red and yellow dress to the party.

In this example, a comma is not needed because the 'and' is connecting two words within the noun phrase "red and yellow dress."

It's worth mentioning that using a Grammar Checker such as Linguix can be a valuable tool to identify and correct these common mistakes. Linguix checks your writing for grammar, punctuation, and style errors, helping you to improve your overall writing skills.