Grammar
Linking words for cause, result, and purpose
Nadia charged her phone because she needed a map. She needed a map, so she charged her phone. The events are the same, but the linking word changes the direction of the explanation.
Choose a linking word or phrase that clearly shows a cause, a result, or a purpose.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
We left early so that we could catch the last train. /wi left ˈɜːli səʊ ðət wi kʊd kætʃ ðə lɑːst treɪn/
The short answer
Use because, since, or because of to give a cause. Use so, therefore, or as a result to give a result. Use to, in order to, or so that to show purpose. The grammar after the linker matters as much as its meaning.
We took the stairs because the elevator was out of order.
Why it works: Because introduces the reason for taking the stairs.
5 more examples
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I stayed at home because I had a fever.
The clause after because gives the reason for staying at home.
Not this:I stayed at home
because of my fever. What changes: Because of is followed by the noun phrase my fever, not a full clause. -
The roads were icy, so the delivery arrived late.
The late delivery is the result of the icy roads.
Not this:The delivery arrived late
because the roads were icy. What changes: This sentence starts with the result and then gives its cause. -
The file was too large. Therefore, the message would not send.
Therefore introduces a result in a separate, more formal sentence.
Not this:The file was too large,
sothe message would not send. What changes: So gives the same relationship inside one joined sentence. -
Mika left early to collect the package.
The infinitive tells us Mika's purpose for leaving early.
Not this:Mika left early
so that she could collectthe package. What changes: So that is followed by a clause and can name the person who has the purpose. -
Since the shop had no batteries, I bought a charger online.
Since gives a reason that helps explain the decision.
Not this:I bought a charger online
because the shop had no batteries. What changes: Because is a direct way to introduce the same reason.
Read the full guide
First ask which idea is the reason and which idea is the consequence. If the second part answers why, choose a cause linker. If it tells the reader what happened next, choose a result linker. If it explains an intended goal, choose a purpose pattern. Then check whether the words after the linker form a clause, a noun phrase, or a verb phrase.
Find the relationship between the ideas
A cause answers why. A result tells what happens because of a cause. A purpose names the goal behind an action. Say the two ideas in your own words first. That small step can stop you from choosing a familiar linker that points in the wrong direction.
The lights went out, so we used a flashlight.
The power cut is the cause. Using a flashlight is the result.
Does so introduce the reason or the consequence in this sentence?
So introduces the consequence: we used a flashlight.
Give a cause with because and because of
Use because before a clause. A clause has a subject and a verb, such as the bus was full. Use because of before a noun phrase or an -ing form, such as the full bus or arriving late. Both patterns give a reason, but they need different grammar.
We waited because the bus was full.
The words after because make a complete clause.
We waited because of the full bus.
The words after because of form a noun phrase.
Which phrase fits before a noun: because or because of?
Use because of before a noun phrase.
Use since when the reason is clear
Since can introduce a cause, especially when the reason is already clear or easy for the reader to accept. It is followed by a clause. Since can also describe time, so check the rest of the sentence to make sure the meaning is clear.
Since the office was closed, I sent the form by email.
Here, since means because. The office closure explains the email.
I have worked from home since the office closed.
Here, since refers to the time when working from home began.
Show a result with so
Use so when the first clause gives the cause and the second clause gives the result. In this pattern, so is usually preceded by a comma. Keep the cause and result close together so the reader can follow the connection.
The museum was crowded, so we booked tickets for another day.
Booking tickets for another day is the decision that followed the crowd.
Complete the pattern: The room was cold, so ... What should come after so?
Add the result, such as we closed the window.
Use therefore and as a result between sentences
Therefore and as a result can make a result especially clear in formal writing. They usually connect complete sentences. Put a full stop or semicolon before them, then use a comma after them when they begin the next sentence.
The payment was not confirmed. As a result, the order stayed open.
The open order follows from the unconfirmed payment.
The payment was not confirmed; therefore, the order stayed open.
The semicolon joins two closely related complete sentences.
Show purpose with to, in order to, and so that
Use to plus the base verb for a simple purpose. In order to has the same basic meaning and is a little more formal. Use so that before a clause when you need to name a subject or use a modal verb such as can, could, or will.
I set two alarms to wake up on time.
To wake up names the goal of setting the alarms.
I set two alarms so that I could wake up on time.
So that is followed by the clause I could wake up on time.
Which purpose pattern is followed by a base verb?
Use to or in order to before a base verb.
Before you go
Remember this
Choose the relationship before you choose the words. Because and because of give causes, so and therefore give results, and to and so that show purpose. Check what follows the linker so that the sentence has the right grammar.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "Linking words for cause, result, and purpose"
What is the difference between because and so?
Because introduces the cause: We left because the store was closing. So introduces the result: The store was closing, so we left. Choose the pattern that matches the direction of your explanation.
I stayed at home because I had a fever.
When should I use because of?
Use because of before a noun phrase or an -ing form, not before a full clause. You can say The game stopped because of the storm. Use because the storm was severe when you need a clause.
I stayed at home because of my fever.
Can I use because and so in the same sentence?
Do not use because and so together for the same cause and result. Write Because the store was closing, we left or The store was closing, so we left. Each sentence already shows the connection.
The roads were icy, so the delivery arrived late.
How do I use therefore in a sentence?
Therefore usually introduces a result after a full stop or semicolon. For example: The address was incomplete. Therefore, the package could not be delivered. In ordinary conversation, so is often more natural.
The delivery arrived late because the roads were icy.
What is the difference between to and so that for purpose?
Use to plus a base verb for a simple goal, as in I saved the receipt to return the item. Use so that plus a clause when you need to name the person or a modal verb: I saved the receipt so that I could return the item.
The file was too large. Therefore, the message would not send.