There are multiple online sentence correction tools nowadays, however, only you are responsible for the quality of your writing. To help you master your grammar and do not rely too much on sentence checkers and fixers, we’ve come up with a list of five tricky mistakes you should avoid.
Mistake #1. Comma in front of “that”
A tricky mistake many people (especially non-native) often make. The rule is that you can put commas before “which,” but not “that.” Let’s have a look at this simple example:
Bad: He’s got a beautiful house, that is located in a good neighborhood.
Good: He’s got a beautiful house, which is located in a good neighborhood.
Important: you can use both “that” and “which,” but you should avoid using commas if the word “that” is critical for your sentence.
Good: He’s got a beautiful house that is located in a good neighborhood.
Mistake #2. Comma splices
A comma splice is a mistake that makes your writing less confident. It arrives when you connect in one sentence two independent clauses and separate them by just a comma with no relevant conjunctions.
You can avoid comma splices in multiple ways:
- Separate your clauses into independent sentences.
- Interesting enough, but while using a comma is a mistake, using a semicolon is totally OK.
- Semicolon plus a transitional word (“however”/”moreover,” etc.) is an even more elegant solution.
- Probably the best thing to do is separating your clauses with coordinating conjunctions (“and”/”but”/etc.).
- Subordinating conjunctions like “although,” “if,” or “since” are totally suitable here as well.
Bad: Jenna is very good at singing, she went to the music school when she was five.
Good: Jenna is very good at singing. She went to music school when she was five.
Mistake #3. “Or” instead of “nor” with “neither”
This mistake is quite tricky to spot and avoid. The standard rule is that if you have “neither” in your sentence, you should use “nor.”
Bad: I like neither burgers or ketchup
Good: I like neither burgers nor ketchup
Also, you can use “nor” if you’re describing more than two objects. However, in such case, you need to put “nor” after each item.
Good: I like neither burgers nor ketchup nor mustard.
Mistake #4. A missing comma after an introductory element
You should put a comma after an introductory word, phrase, or clause. Usually, the introductory word in the sentence is an adverb. Using a comma gives the reader a slight pause after the introduction, which makes it easier to understand the writing.
Bad: Meanwhile the boy went outside to play football.
Good: Meanwhile, the boy went outside to play football.
Mistake #5. Whether vs. If
In English, you use “whether” when you describe a situation where there are two or more alternatives, while ‘if’ is used to express a condition with no other options at all. Remember the difference, and you will always be correct when solving “whether/if” puzzle.
Good: I don’t know whether I will go on vacation this year. (Two possible scenarios: the person either will go on vacation or stay in the city).
Good: I will go on vacation if I get the bonus. (I.e., no vacation if no bonus received – the only possible scenario).
Quick editing checklist
Before you finalize a draft, run a short, systematic pass to catch the five tricky errors covered above. A focused sweep is faster and more reliable than relying on memory alone.
Work in two stages: first fix sentence-level structure (comma splices, missing commas after intros), then check word choices and pairings (that/which, neither/nor, whether/if).
Read sentences aloud-pauses often reveal where commas belong and where joins feel awkward.
- Don’t put a comma before “that”; reserve commas with “which” when the clause is nonessential.
- Fix comma splices by adding a conjunction, using a semicolon, or splitting into two sentences.
- Use “nor” after “neither,” and repeat “nor” for additional listed items.
- Always add a comma after introductory words, phrases, or clauses to signal a pause.
- Use “whether” to show alternatives or reported uncertainty; use “if” for conditional situations.
FAQ
When is a comma before “that” acceptable?
Almost never. If the clause is nonessential and set off by commas, prefer “which.” Use “that” without commas when the clause defines or restricts the noun.
How can I spot a comma splice quickly?
Check if both parts around a comma can stand alone as full sentences. If they can, the comma alone is incorrect-add a conjunction, use a semicolon, or split into two sentences.
How do I choose between “whether” and “if”?
Use “whether” when presenting alternatives or expressing uncertainty about two or more outcomes. Use “if” to state a condition that determines a single outcome; when unclear, rephrase the sentence to make the relationship explicit.