Commas with essential and non-essential clauses

With essential and non-essential clauses it is important to know whether to use commas or not because their use or avoidance will change the meaning of the sentence.

Essential clauses are necessary to identify the person or thing that is being described. They are essential to understanding the sentence. They restrict the meaning to that specific person/thing. For example:

Mr brother who lives in Australia came to see us last week. (I have 5 brothers)

The man who saved my son's life is a retired teacher.

The clauses in italics are essential to the understanding of the sentences. If they are removed, the sentences lose their meaning. These clauses often start with who, which or that. We do not use commas with clauses of this kind.

Non-essential clauses are not essential to the understanding of the sentence since they merely supply some additional information. They can be omitted from the sentence without changing the basic meaning. For example:

My sister, who lives in China, came to stay yesterday. (I've only one sister.)

The woman, who was dressed in a bright red coat, came running up to us.

Clauses like this often start with who or which but never that. When we use clauses of this type, we must enclose them with commas.

Try reading aloud the four examples given above. What do you notice? You might have noticed that where we place commas (with non-essential clauses), we also place a pause in our speech.

Look at these sentences and decide which ones contain non-essential clauses and need pairs of commas. Then look at the notes that follow.

  • The man whom I had never met before offered to lend me his car.
  • Mrs. Smith who is a retired teacher does voluntary work at the centre.
  • People who speak Kiswahili are eligible to apply for this job.
  • Linda who speaks Kiswahili should apply for the job.
  • Carmen who missed the class yesterday had to explain her absence to the teacher.
  • All the students who missed the class were given extra homework.
  • The scientist who lectured at the university yesterday predicted another early breakthrough.
  • Dr. Robbins who lectured at the university last night warned of an ecological disaster.
  • Rice which is grown in many countries is a staple food throughout much of the world.
  • The canals which lie between Manchester and London are becoming a very popular means of transport.

Notes:

Where the information in the clause is essential to understanding, we do not place commas within the sentence. Where the sentence contains some interesting but not essential information, we include the commas.

  • The man, whom I had never met before, offered to lend me his car.
  • Mrs. Smith, who is a retired teacher, does voluntary work at the centre.
  • People who speak Kiswahili are eligible to apply for this job.
  • Linda, who speaks Kiswahili, should apply for the job.
  • Carmen, who missed the class yesterday, had to explain her absence to the teacher.
  • All the students who missed the class were given extra homework. (If every one of the students had missed the class, we would have placed commas around who missed the class.)
  • The scientist who lectured at the university yesterday predicted another early breakthrough.
  • Dr. Robbins, who lectured at the university last night, warned of an ecological disaster.
  • Rice, which is grown in many countries, is a staple food throughout much of the world.
  • The canals which lie between Manchester and London are becoming a very popular means of transport. (In other words, we want to specify precisely what canals we are referring to. Whether we include commas or not depends on the meaning we want to convey. If we have already been talking about these canals and you simply want to specify more clearly where they are, we would place commas around which lie between Manchester and London.)

Task

Now practise the general use of commas. Do you think that any of these sentences require additional commas?

  • I tried to creep quietly down the stairs but despite my efforts they heard me and took me back.
  • Because of the continuing fighting the UN was unable to continue the relief mission.
  • Tony Blair the main speaker made the last speech.
  • My brother who is a dentist enjoys watching soap operas. (I've one brother.)
  • My brother who is a dentist enjoys watching soap operas. (I have 4 brothers)
  • She's a lovely dancer but a lousy skater.
  • His latest film Notting Hill has been very successful.
  • Finally after much hesitation he came to the point.
  • Underneath the garage was on fire.
  • However subsequent research studies were unable to replicate the same results.
  • The project which involved a range of departments from different universities was funded by an EU research grant.
  • Domestic violence and especially violence against women can be a problem in all cultures however it has been particularly difficult to conduct research into this issue in the Muslim community for this study.

Notes on the Task

  • I tried to creep quietly down the stairs but, despite my efforts, they heard me and took me back.
  • Because of the continuing fighting, the UN was unable to continue the relief mission.
  • Tony Blair, the main speaker, made the last speech.
  • My brother, who is a dentist, enjoys watching soap operas. (I've one brother.)
  • My brother who is a dentist enjoys watching soap operas. (I have 4 brothers)
  • She's a lovely dancer, but a lousy skater.
  • His latest film, Notting Hill, has been very successful.
  • Finally, after much hesitation, he came to the point.
  • Underneath, the garage was on fire.
  • However, subsequent research studies were unable to replicate the same results.
  • The project, which involved a range of departments from different universities, was funded by an EU research grant.
  • Domestic violence, and especially violence against women, can be a problem in all cultures. However, it has been particularly difficult to conduct research into this issue in the Muslim community for this study.

 

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