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English: skills for learning
English: skills for learning

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6.1 Connecting sentences with ‘if’ and ‘when’

Compound sentences are formed by connecting two or more clauses which could stand on their own with the same meaning even if they were separated.

Complex sentences differ from compound sentences in that their meaning depends on the combination of the two statements, so that the two clauses cannot stand on their own.

The most common words used to connect sentences in this way are if and when.

Activity 11

Timing: Allow approximately 10 minutes

Look at this example:

If children’s diets are low in energy

Does this clause make sense to you? Is it clear?

This clause needs to be joined to another one in order to be meaningful.

For example:

If children’s diets are low in energy, they will stop growing and gaining weight.

The two clauses are combined as shown below.

somebodydoes or issomething
subjectverbobject (or rest of the clause)
First clausechildren’s dietsarelow in energy
Second clausetheywill stop growing and gainingweight

Each of the above clauses has a meaning on its own but, when if is added, it means that not all children’s diets are low in energy and not all of them will stop growing and gaining weight.

Sentences with if and when cannot stand alone but must always combine two clauses. The meaning of one of the clauses always depends on the meaning of the other.

Now look at another example:

When people suffer from malnutrition, they are often deficient in the vitamins and minerals needed by the body.

As with the example using ‘if’, this sentence consists of two clauses which include a subject, verb and the object or rest of the clauses:

somebodydoes or issomething
subjectverb object or rest of the clause
First clausepeoplesufferfrom malnutrition
Second clausetheyareoften deficient in the vitamins and minerals needed by the body

Again, each of these clauses has a meaning, but that meaning is changed by the addition of when when both are combined into a sentence. This makes it clear to the reader that it is only when people are deficient in the vitamins and minerals needed by the body that they may suffer from malnutrition.

A sentence containing if or when which does not combine two clauses doesn’t make sense.

Connecting sentences with ‘if’ and ‘when’

Match each of the clauses below with a suitable clause starting with If or When from the left-hand column to make a sensible sentence.

Using the following two lists, match each numbered item with the correct letter.

  1. they tend to maintain this practice into adulthood.

  2. their level of concentration suffers.

  3. call the out-of-hours number provided.

  4. you will put on weight.

  5. take the next dose as normal.

  6. you are less likely to have heart disease.

  • a.1. If children are introduced to good dental hygiene early,

  • b.5. If you forget to take your medicine,

  • c.4. If you take in more calories than your body consumes,

  • d.3. If the surgery is closed,

  • e.6. If you take regular exercise,

  • f.2. When people don’t sleep enough,

The correct answers are:
  • 1 = a
  • 2 = f
  • 3 = d
  • 4 = c
  • 5 = b
  • 6 = e


Note how clauses beginning with ‘If’ or ‘When’ end in a comma. You will see more examples of this in the next activity.