Reduced relative clauses are shortened versions of relative clauses. They are also known as reduced adjective clauses.
Relative clauses usually modify a noun or noun phrase in the sentence as in this example, where the word 'table' is being modified:
In this reduced clause, 'that' is no longer used:
However, it is not always just a matter of omitting the relative pronoun. There are different reduced relative clause rules depending on the sentence involved.
Reduced relative clauses are mainly created through the use of:
We'll now look at each of these in turn.
if the relative pronoun is the subject of the relative clause, then the clause can be reduced to a present participle (verb + ing) phase or past participle (verb + ed) phrase.
If the verb is in the active voice, it gets reduced to a present participle phrase.
Any active tense can be changed to a present participle phrase e.g. present simple, past simple, present continuous, present perfect etc.
To do this you delete the relative pronoun and any auxiliary verbs if there are any, and use the present participle of the main verb. If it is a negative sentence, then we use 'not' at the beginning of the participle phrase.
Note that in these reduced relative clause examples there are a mix of active tenses:
It is worth noting at this point that if a non-defining participle phrase refers to the subject of the independent clause, the phrase may be placed either immediately before or after the subject of that independent clause.
So in the case of this sentence, 'having finally voted' refers to the MPs in the independent clause (MPs are leaving parliament), so it can be placed in two positions:
If the relative clause is in the passive voice and in a simple tense, then it can be reduced by deleting the relative pronoun and the verb 'to be', leaving you with the past participle.
If it is a negative, then you place 'not' at the beginning of the participle phrase.
If it is in the passive voice but is a continuous tense verb (present or past), then you delete the connecting word and 'to be', leaving you with 'being + past participle'.
You then have a continuous passive participle phrase.
If the clause in the passive perfect tense (present or past), then 'have' or 'had' is replaced by 'having'. So we end up with 'having + been' to make the reduced relative clause.
This is a perfect passive particle phrase:
Again, if the non-defining participle phrase refers to the subject of the independent clause, the phrase may be placed either immediately before or after the subject of that independent clause:
In the case of the perfect tenses, you can choose either a present or past participle, depending on what you wish to emphasise in the sentence.
If you wish to emphasise the prior completion of the activity in the participle phrase, 'have' is changed to 'having', leaving you with 'having + past participle'.
You will then have formed a perfect active participle phrase:
So in the above example, it emphasised that the hard studying took place before the best results.
If you do not wish to emphasise in the particle phrase the prior completion of the activity, then it is more common to use the present participle.
In this case 'have' is omitted and the main verb of the relative clause is changed to the present participle.
We've been looking at present and past participle phrases, but it should also be noted that we can in cases reduce relative clauses with just a past particle.
We can do this if the sentence has the verb 'to be' or 'to have' and only a past participle. In this case we can move the past participle to before the modified noun.
If the relative pronoun is followed by a prepositional phrase, then this can be reduced.
If the relative clause has only an adjective and the verb to be within it, then the adjective can be placed before the noun, and the relative pronoun (and verb 'to be') can be deleted:
If there is a verb other than the verb to be (usually sense verbs such as smell, look, feel, sound etc), then we reduce it to an adjective phrase:
Reduced relative clauses can be used to make your writing more concise, so it is common to use them within formal or academic writing, though they can appear in any style of writing.
As the grammatically correct reduction of relative clauses is quite a difficult skill, it is something the examiner in the IELTS test will look out for when awarding a band 7 and above for grammatical range and accuracy.
Note though that this will NOT include reducing relative clauses to propositional phrases, adjective phrases, or adjectives because when you do this you are creating a more simple sentence. However, reduced relative clauses in the form of present and past participle phrases is seen as a higher level skill.