Grammar
Subordinate clauses: form, function, and punctuation
Because the bus was delayed, we arrived late. The first part gives a reason, but it needs the main clause to make a complete sentence.
Identify a subordinate clause and join it to a main clause with a suitable connector, clear word order, and punctuation.
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
Although the route looked short, it took an hour. /ɔːlˈðəʊ ðə ruːt lʊkt ʃɔːt ɪt tʊk ən ˈaʊə/
The short answer
Use a subordinate clause to add information to a main clause. Place it before or after the main clause. When it comes first, use a comma before the main clause. Choose a connector that shows the relationship you mean, such as because for a reason, if for a condition, or although for a contrast.
When the clinic opens, I will call for an appointment.
Why it works: When the clinic opens is a subordinate clause. It tells us when the speaker will call.
5 more examples
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Because the bus was delayed, we arrived after the meeting began.
This subordinate clause gives the reason for the late arrival. It comes first, so a comma separates it from the main clause.
Not this:We arrived after the meeting began
because the bus was delayed. What changes: The same reason clause comes after the main clause. A comma is not usually needed before because here. -
Although the route looked short, it took an hour.
Although introduces a contrast between the route's appearance and the time it took.
Not this:The route looked short,
butit took an hour. What changes: But joins two main clauses. Although introduces a subordinate clause instead. -
If the printer stops again, call the support desk.
If introduces the condition for calling the support desk.
Not this:Call the support desk
if the printer stops again. What changes: The condition can follow the main clause when the meaning stays clear. -
When you finish the form, save a copy.
When adds the time for the instruction in the main clause.
Not this:Save a copy
when you finish the form. What changes: The time clause follows the instruction, so it does not usually need a comma. -
The colleague who manages bookings is away today.
Who manages bookings is a relative clause. It identifies which colleague the speaker means.
Not this:
The colleagueis away today. What changes: Without the relative clause, the listener may not know which colleague is meant.
Read the full guide
First, look for the part that can stand alone. In We stayed inside because the wind was strong, We stayed inside is a complete main clause. Because the wind was strong explains the reason, but it cannot usually stand alone in formal writing. The connector tells you how the two ideas relate.
Find the main clause first
A main clause gives a complete idea. Start by finding the part that could stand as a sentence. The other part may give extra information, but it needs the main clause to complete its meaning.
We stayed inside because the wind was strong.
We stayed inside is the main clause. Because the wind was strong gives the reason for that action.
Because the wind was strong.
This is a subordinate clause. It gives a reason, but it does not tell us what happened.
Which part can stand alone: 'the lights went out' or 'when the storm began'?
Use the lights went out. It has a complete meaning without another clause.
Choose a connector for the relationship
The first word of a subordinate clause often shows its job. Because gives a reason. Although gives a contrast. When and before give time. If gives a condition. Choose the word that matches the relationship between the two ideas.
We left early because the last bus stops at ten.
Because explains why the group left early.
Although the café was busy, we found a table.
Although shows a contrast between the busy café and the available table.
Which connector fits a condition: because, if, or although?
Use if. It introduces the situation that must happen before the result can happen.
Put a comma after an opening subordinate clause
A subordinate clause can come before the main clause. When it does, use a comma to show where the opening information ends and the main statement begins. When the main clause comes first, a comma is not usually needed before a following because, if, or when clause.
If the weather improves, we will eat outside.
The condition comes first, so a comma separates it from the main clause.
We will eat outside if the weather improves.
The main clause comes first. The following if clause does not usually need a comma.
Add the punctuation: 'When the files are ready ___ send them to the team.'
Write a comma after ready: When the files are ready, send them to the team.
Keep normal word order in a subordinate clause
A subordinate clause normally keeps the same subject and verb order as a statement. This is especially useful with indirect questions and clauses after if, because, and when. Do not turn the clause into a question just because it begins with a question word.
I do not know where the nearest pharmacy is.
Where the nearest pharmacy is is an indirect question clause. The subject comes before is.
She asked whether the office was open.
Whether introduces a clause with normal statement order: the office was open.
Choose the correct clause: 'where the station is' or 'where is the station'?
Use where the station is after I know, I asked, or a similar expression. It is part of a larger sentence, not a direct question.
Use relative clauses to identify or describe a noun
A relative clause gives more information about a noun. Who often refers to people, which often refers to things, and that can refer to people or things in many defining clauses. The clause depends on the noun it describes.
The neighbor who owns the red bicycle is a mechanic.
Who owns the red bicycle identifies the neighbor. It cannot stand alone as the full message.
Please return the charger that you borrowed.
That you borrowed identifies which charger the speaker means.
Which word usually refers to a person in a relative clause: who or which?
Use who for a person: the colleague who answered the call.
Avoid two common connector mistakes
Use one connector to make the relationship clear. Do not combine because with so in the same reason-and-result structure. Also check that a word such as although introduces a contrast rather than a reason or condition.
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Not this:
Because the road was closed, so we took the train.Say: Because the road was closed, we took the train.
Because already introduces the reason clause. The main clause gives the result.
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Not this:
Although the alarm rang, because I woke up.Say: Although the alarm rang, I did not wake up.
Although needs a contrasting main clause, not a second reason connector.
Choose the complete sentence: 'Because I missed the bus' or 'Because I missed the bus, I walked home.'
Use Because I missed the bus, I walked home. The main clause completes the reason.
Before you go
Remember this
A subordinate clause depends on a main clause. Use its connector to show the link between the ideas. Put a comma after a subordinate clause when it comes first, and keep normal subject and verb order inside the clause. Read both parts together to check that the sentence is complete.
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
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Try the written questionsQuestions about "Subordinate clauses: form, function, and punctuation"
What is a subordinate clause?
A subordinate clause has a subject and a verb, but it depends on a main clause to complete its meaning. Because the bus was delayed gives a reason, but it does not say what happened. Add a main clause to make a complete sentence: Because the bus was delayed, we arrived after the meeting began.
Because the bus was delayed, we arrived after the meeting began.
Which words introduce subordinate clauses?
Common subordinating conjunctions include because, although, if, when, while, before, after, until, and since. Each one shows a relationship between ideas. Because gives a reason, if gives a condition, and when gives a time. Relative words such as who, which, and that can also introduce a clause that describes a noun.
We arrived after the meeting began because the bus was delayed.
When do I use a comma with a subordinate clause?
Use a comma after a subordinate clause when it comes before the main clause: When you finish the form, save a copy. When the main clause comes first, you do not usually need a comma: Save a copy when you finish the form. This pattern also works with many if, because, and although clauses.
Although the route looked short, it took an hour.
What is the difference between although and but?
Both although and but can show contrast, but they join clauses in different ways. Although introduces a subordinate clause: Although the route looked short, it took an hour. But joins two main clauses: The route looked short, but it took an hour. Do not use both to join the same two ideas.
The route looked short, but it took an hour.
Do subordinate clauses use question word order?
No. A subordinate clause after an expression such as I know or She asked usually uses statement word order. Say I do not know where the nearest pharmacy is, not I do not know where is the nearest pharmacy. The clause is part of a larger sentence, so the subject comes before the verb.
If the printer stops again, call the support desk.