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.

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.

 

Semi-colons and colons

A semi-colon [; ] is a bit like a 'soft' full stop; wherever you can place a semi-colon, you can also place a full-stop. The writer may decide to use a semi-colon when there is an extra piece of related information to give to the reader which is closely related to the sentence before, and which the writer feels does not really require a sentence of its own. It is, in other words, used to join two parts of a sentence that could otherwise be left as two sentences.

It is very important to note that a semi-colon can never be replaced by a comma but this is often an error that writers make. In the two following examples, we could not use a comma:

I looked long and hard for the right material; nothing else would do.

The whole team was looking exhausted; Maria was clearly showing the strain.

A semi-colon can also be used for complicated lists, in collaboration with commas. For example:

The research study explored a number of geographical areas: the southern parts of Wales, Scotland and Ireland; the northerly tip of the Hebrides; the most north-western tip of France.

A colon [: ] is used to introduce a list, just as in the sentence above.

There are a number of possible solutions: medical, herbal or alternative.

The research team visited several sites: Larkness, Coaster and Ariemes.

A note on the use of however.

The word however is commonly used in academic writing and it is important to remember how it is used.

At the start of a sentence, it is normally followed by a comma.

However, Johansen’s later research was more productive.

When the word however appears in the middle of a sentence to introduce a contrast, it must follow a semi-colon and it must be followed by a comma.

The data suggest that foreign direct investment can have a significant affect on local industry; however, further research will be needed to confirm this finding.

The pattern of canals across the country provided a cheap and effective way to transport heavy goods for a hundred years; however, the development of a railway network would change all that.

 

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