What does "Unless" mean? How to use the structure "Unless" and exercises with answers

The structure "Unless" may not be unfamiliar to those learning English due to its popularity. However, not everyone knows exactly how to use "Unless" in specific cases. Let’s explore all the information related to the "Unless" structure in the article below!

I. What is "Unless"?

"Unless" is pronounced /ənˈles/ and is used with a negative meaning, which translates to "except if". It can be viewed as a conjunction in a sentence to connect clauses. "Unless" is synonymous with the structure "If...not." Like "If," "Unless" can be followed by the present tense, past tense, or past perfect tense. For example:

• You won't be able to finish this job unless you work all night. 

•  Unless you come 30 minutes early, you won't have a seat at this forum. 

Some words/phrases/similar structures that are synonymous or close in meaning to "unless":

II. Position of the "Unless" Clause

In conditional sentences, we do not need to worry about the position of the clause within the sentence. The clause containing "unless" can appear either before or after the main clause. For example:

• Unless my boyfriend apologizes to me first, I will never forgive him. 

• You won't get a bonus unless you exceed the KPI by 120%. 

III. How to Use the "Unless" Structure

Below are the most common uses of "unless"; let's explore them!

1. The "Unless" Structure in Conditional Sentences

Conditional sentences are the most common type where we can use "unless." Here is how to use and the formula for "unless" in the most common types of conditional sentences:

1.1. The "Unless" Structure in Type 1 Conditional Sentences

The "unless" structure in type 1 conditional sentences is used to express situations that might occur in the future. "Unless" and "if not" can be used interchangeably. The structure is:

Unless + S + V (present simple), S + will/can/shall + V

Or

S + will/can/shall + V unless + S + V (present simple)

For example:

• I won't be able to get this job unless I practice for the interview thoroughly. 

• Unless I practice for the interview thoroughly, I won't be able to get this job. 

= If I don’t practice for the interview thoroughly, I won't be able to get this job 

1.2. The "Unless" Structure in Type 2 Conditional Sentences

The "unless" structure in type 2 conditional sentences is used to express a situation that cannot happen in the present. "If not" and "unless" can be used interchangeably. The structure is:

Unless + S + V-ed/V2 (simple past), S + would + V

Or

S + would + V unless + S + V-ed/V2 (simple past)

For example: 

• I wouldn't be in so much pain unless I loved him so much. 

• Unless I loved him so much, I wouldn't be in so much pain. 

= If i didn’t love him so much, I wouldn't be in so much pain. 

1.3. The "Unless" Structure in Type 3 Conditional Sentences

The "unless" structure in type 3 conditional sentences is used to express a situation that did not happen in the past. "If not" can be used interchangeably with "unless" and vice versa. The structure is:

Unless + S + had + Ved/V3, S + would + have + Ved/V3

Or 

S + would + have + Ved/V3 Unless + S + had + Ved/V3

For example:

• Anna wouldn't have beenlate for work this morningunless she had stayed up late for the party yesterday. 

• Unless she had stayed up late for the party yesterday, Anna wouldn't be late for work this morning. 

= If Anna hadn’t stayed up late for the party yesterday, she wouldn’t have been late for work this morning. 

1.4. The "Unless" Structure in Mixed Conditional Sentences

The "unless" structure in mixed conditional sentences is used to express the relationship between an event in the past and its result in the present or future. "If not" can be used interchangeably with "unless" and vice versa. The structure is:

2. The "Unless" Structure Used to Suggest Opinions

You can use the "unless" structure to suggest opinions; in this case, it is important to note that you should not use "if...not" to replace "unless." For example:

• Bella will come to my birthday party - unless she is busy. 

• I will go to the writing competition award ceremony - unless I am invited. 

3. The "Unless" Structure as a Warning

You can use the "unless" structure to emphasize or urge an action that needs to be taken urgently to avoid consequences. In this case, it is not advisable to use "if not" as a replacement, as it will not express the correct nuance.

For example:

• Unless Jack hurries up, he will miss his girlfriend at the airport. 

• Unless Bella applies for the job soon, she will miss a good opportunity. 

4. Notes on Using the "Unless" Structure

Here are some important notes to help you use the "unless" structure correctly:

• "Unless" already carries a negative meaning, so "unless" should only be used with affirmative sentences.

• "Unless" is not the same as "if not" (note that "if not" is written as one phrase). "If not" is a type of implicit conditional statement. It is used to express the opposite idea compared to the preceding clause. If the preceding clause is affirmative, then "if not" expresses the negative meaning, and vice versa. For example: Bella won’t come tomorrow; if not, everything will become very difficult.

IV. Guidelines for Rewriting Sentences with the "Unless" Structure

The type of English writing exercise involving "unless" appears quite frequently and in various forms. The given sentences that require rewriting with the "unless" structure often include:

• Type 1, 2, and 3 conditional sentences

• Inverted sentences

• Sentences with equivalent conjunctions to "if"

• Implicit conditional sentences

One useful tip that PREP wants to introduce to you for mastering the exercise of converting from "if...not" to "unless" and vice versa is to transform the sentence in two steps as follows:

• Step 1: Transform the sentence into the traditional form (using "if").

• Step 2: Convert it into the "unless" form.

For example: Study harder. Otherwise, you will failthe exam. 

• Step 1: We can change it to the traditional form as follows: If you don’t study harder, you will fail the exam.

• Step 2: Then we convert it into the form containing the "unless" structure: Unless you study harder, you will fail the exam.

Once you are familiar with this process, you can directly convert to "unless" right away. One more small note is to ensure you understand the meaning of the original sentence. After that, when rewriting the sentence, check if the meaning of the new sentence matches the original one in order to avoid mixing it up with complex structures.

V. Common Mistakes When Using the "Unless" Structure

Here are some common mistakes you might encounter when using "unless." Please read carefully to avoid these errors:

1. Using the "Unless" Structure in Questions

In questions, you can only use "if not" and cannot replace it with "unless." For example:

• What will happen if I do not come to your party tomorrow? ⏩ In this case, you cannot say: What will happen unless I come to your party tomorrow?

• What will happen if this contract is not signed today? ⏩ In this case, you cannot say: What will happen unless this contract is signed today?

2. Using "will""would" in Clauses with "Unless"

In clauses with "unless," we should not use "will" or "would." For example:

• Unless you go to sleep soon, you will be exhausted and have a headache. ⏩ Incorrect usage: Unless you will go to sleep soon, you will be exhausted and have a headache.

• Unless he proposes soon, she will break up with him. ⏩ Incorrect usage: Unless he will propose soon, she will break up with him.

3. Using "Unless" to Express the Meaning of "If"

You cannot use "unless" to replace a sentence that has the meaning of "if." For example:

• Tom will help her if his sister can’t make it. ⏩ Incorrect usage: Tom will help her unless his sister can’t make it.

• Lucky will go to the beach if his girlfriend isn’t busy. ⏩ Incorrect usage: Lucky will go to the beach unless his girlfriend isn’t busy.

VI. "Unless" Exercises with Detailed Answers

Exercise 1: Choose the most accurate answer

1. Let’s go for a jog  – ______ you look too tired.

1. unless

2. if

2. He will take the project ________ the pay is too low.

1. unless

2. if

3. Lan will be back home tomorrow _______ there is a plane strike.

1. unless

2. if

4. We will be surprised_______ he doesn’t come soon.

1. unless

2. if

5. I think Rose would look prettier ______ She didn’t wear so much make-up.

1. unless

2. if

6. She is going to the office this afternoon, ______ it rains.

1. unless

2. if

7. ________ you don’t stop drink milk tea and fast food, you will gain weight fast

1. unless

2. if

8. _______ Mary starts now, she will not reach there in time.

1. unless

2. if

9. ______ she was rich, she would spend all my time traveling and shopping.

1. unless

2. if

10. ______ we have enough time tomorrow, certainly we will come and see you.

1. unless

2. if

Exercise 2: Rewrite the following sentences so that the meaning remains unchanged:

1. If Bella doesn't study harder, she will fail the test.

➡ Unless ………………………………………………………………..

2. If John doesn’t practice writing every day, he can’t improve her IELTS writing skills.

➡ Unless ………………………………………………………………..

3. Unless Anna is a professional driver, she can’t help you move by car from the hall. 

➡ If ………………………………………………………………..

4. Unless you stop take a shower late at night, you might fall ill.

➡ If ………………………………………………………………..

5. If Mary doesn’t return this book tomorrow, she will have to pay a fine.

➡ Unless ………………………………………………………………..

6. Unless Clara cleaned up her bedroom now, her mother could ask her to do this.

➡ If …………………………………………………………………

7. Unless Jack were absent now, he would meet the headmaster.

➡ If …………………………………………………………………

8. If you didn’t know the number, you would not ring this restaurant and book a table.

➡ Unless …………………………………………………………………

9. If John’s sister didn’t have a terrible toothache she wouldn’t be absent from the important meeting.

➡ Unless …………………………………………………………………

10. If Rose didn’t study English hard, he could not get a scholarship.

➡ Unless ………………………………………………………………..

Answer keys

This article provides the essential knowledge you need to firmly understand the "unless" structure. Don't forget to complete the practice exercises to help you remember and master this structure better. Follow PREP for more knowledge, Preppies!