What Are Relative Clauses?

Relative clauses are parts of a sentence that give more information about a noun or pronoun. They connect two ideas into one smoother sentence.

They usually start with a relative pronoun like who, which, that, whose, or a relative adverb like where, when, why.

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Defining vs. Non-Defining: What’s the Difference?

There are two main types of relative clauses: defining and non-defining.

• Defining Relative Clauses: These clauses provide essential information. The sentence’s meaning changes or becomes unclear if you remove them. They answer the question “Which one?” or “What kind?”
• Non-Defining Relative Clauses: These clauses give extra, non-essential information. You can remove them, and the main meaning of the sentence will stay the same. They add interesting details.

Why Are Commas Important in Relative Clauses?

Punctuation is the key difference between defining and non-defining clauses.

• Defining clauses do NOT use commas. They are directly connected to the noun they describe.
• Non-defining clauses ALWAYS use commas to separate them from the rest of the sentence. Think of the commas like parentheses, showing that the information is extra.

Using commas incorrectly can change the meaning of your sentence completely. For example:

• The sports facilities which are not in regular use will be sold. (Only the unused facilities will be sold.)
• The sports facilities, which are not in regular use, will be sold. (All sports facilities will be sold, and by the way, none are in regular use.)

Which Relative Pronouns Can You Use?

The choice of relative pronoun depends on whether the clause is defining or non-defining, and if you are talking about people or things.

In Defining Relative Clauses:

• For people: 使用方法 who または that.
• For things: 使用方法 which または that.

In Non-Defining Relative Clauses:

• For people: 使用方法 who.
• For things: 使用方法 which.
• Important: You CANNOT use that in non-defining relative clauses.

Can You Omit Relative Pronouns?

Sometimes you can leave out the relative pronoun, but only in specific situations.

• When to omit: You can omit the relative pronoun (like who, which, that) in a defining relative clause if it is the object of the verb in the relative clause.
• When NOT to omit: You must include the relative pronoun if it is the subject of the verb in the relative clause. You also cannot omit pronouns in non-defining clauses.

What About ‘Where’, ‘When’, and ‘Why’?

Besides pronouns, you can also use relative adverbs to introduce clauses.

• Where refers to a place.
• When refers to a time.
• Why refers to a reason.

In defining relative clauses, you can sometimes omit when そして why.

例

• The girl who is studying to become a vet is called Sarah.
• Sarah, who is 20, is studying to become a vet.
• The boy who is playing is the county champion.
• The teacher that I met is the Head of Maths.
• Colours which can be worn are black, navy and grey.
• The book that I recommend costs £8.50.
• Ted, who plays the violin, is living above a music shop.
• The new brand of shampoo, which is selling well, contains only natural ingredients.
• The hotel where we stayed had a beautiful garden.
• Christmas is the time (when) many people start thinking about their next holiday.
• That’s the reason (why) I left early.

練習

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スペイン語話者がよく犯す間違い

1. Using that in non-defining clauses:

Many learners incorrectly use that in non-defining clauses. Remember, that is only for defining clauses.

• 誤り： My car, that is red, is very fast.
• 正しい： My car, which is red, is very fast.

2. Missing commas in non-defining clauses:

Forgetting commas is a common error that can change your sentence’s meaning.

• 誤り： My brother who lives in Canada is visiting. (This implies you have more than one brother, and you are specifying which one.)
• 正しい： My brother, who lives in Canada, is visiting. (This implies you have one brother, and you are adding extra information about him.)

3. Adding commas to defining clauses:

Defining clauses should not have commas.

• 誤り： The book, that I read, was excellent.
• 正しい： The book that I read was excellent.

よくある質問

What is the main difference between defining and non-defining relative clauses?

The main difference is whether the information is essential or extra. Defining clauses give essential information and use no commas. Non-defining clauses give extra information and are always separated by commas.

Can I always use ‘that’ instead of ‘who’ or ‘which’?

No. You can use that ～の代わりに who または which only in defining relative clauses. You cannot use that in non-defining relative clauses.

When can I leave out the relative pronoun?

You can leave out the relative pronoun (like who, which, that) only in defining relative clauses when it is the object of the verb in the relative clause. If it’s the subject, you must keep it.

How are relative clauses tested in the B2 First exam?

Relative clauses often appear in the B2 First (FCE) Use of English paper. You might find them in Part 2 (Open Cloze), where you need to provide the correct relative pronoun, or in Part 4 (Key Word Transformation), where you may need to rewrite a sentence using a relative clause correctly, paying attention to punctuation.

関連レッスン

• Defining and non-defining relative clauses
• Defining and non-defining relative clauses
• Defining and non-defining relative clauses
• Defining and non-defining relative clauses