Grammatical Features of EST：Postmodifiers

Postmodifiers occur after a noun or a noun phrase. We have the following range of 

postmodifiers ；

1. Relative Clauses

2. Prepositional Phrases

3. Non-finite Clauses Equivalent to Relative Clauses (Non-finite Verbs)

4. Appositive Clauses

Example: His main argument, that scientific laws have no exceptions, was considered to be problematic.

5. Clauses of Time, Place, Manner and Reason

Examles： There came a time when earthquakes crumpled the earth. (Time) In every case where work is done two things enter： 1) the exertion of a force and 2) the movement of something by that force. (Place) This is the same way that your eyes move when you read a book. (Manner) This is the reason why moving bodies have energy. (Reason)

6. Adverbs

Example: The condition here is poor.

7. Adjectives

Example: There's something wrong with the motor.

Among all these postmodifiers. Relative Clauses, Nonfinite Clauses and Prepositional Phrases are more often used in EST writings. Since we have already mentioned Non-finite clauses in the section on conciseness, it seems unnecessary to deal with other than Relative clauses and Prepositional Phrases in the following.  

I. Relative Clauses

Relative clauses are sub-clauses which are linked to part or all of the main clause by a back-pointing element, usually a Relative Pronoun. The principal function of a relative clause is that of postmodifier of a noun or a noun phrase, where the relative pronoun points back to the Antecedent.

1) Relative Clauses (Defining)

Look at the following sentences: a. Loads cause tensile stresses. b. Loads tend to pull a body apart. If the noun phrases refer to the same thing, we can combine the two sentences into one by using a relative clause； c. Loads which tend to pull a body apart cause tensile stresses. In sentence c. the relative clause is a necessary part of the idea； if it is left out, the sentence does not make complete sense. The "which" clause defines the antecedent and gives it its definite connotation. Clauses of this type are called Definite Clauses. 

2) Relative Clauses (Non-defining)

Compare the following sentences ；

a. The mill which produces sheet steel was built in Manchester but the one which produces tube steel was built in Edinburgh.

b. The mill, which produces sheet steel, was built in Manchester.

In sentence b, the relative clause could be omitted and the rest of the sentence would still make perfect sense. The relative clause here is a kind of parenthesis, a casual remark, an aside or an explanation.

In sentence a, the relative clauses tell us which mill we are talking about, they are two defining relative clauses.  In sentence b, we already know which mill we are talking about. The clause simply adds some extra information about the mill, and it is a non-defining relative clause. (Note the use of commas.)

3) Relative Clauses with Prepositions

In EST writings we find many relative clauses with a preposition before“which”. Such clauses are formed in the following way:

Any chemical process is called a chemical reaction.

Certain substances are converted into other substances in the process.

=Any chemical process in which certain substances are converted into other substances is called a chemical reaction.