A few words about sentences

At its most basic a sentence has two parts: a subject and a predicate. To be a complete sentence it must have both parts. In some writing incomplete sentences are fine, but in business writing it’s best to write complete sentences (writing sales copy is probably the only exception to this).
 
First some quick definitions…
 
Subject: who or what the sentence is about
Predicate: says something about the subject
The shortest complete sentence in English is:
I am.
‘I’ is the subject. ‘Am’ is the predicate.
 
To find the subject of your sentence, first find the main verb and then ask ‘who?’ or ‘what?’
 
Example:
Yesterday, after lunch, the client contacted me.
The main verb is ‘contacted’. Who or what contacted? The client.
But it’s not always simple…
 
 
Both parts of the sentence can be simple, complex or compound, or a combination of each.
This is where a careless writer may get into trouble, writing long, rambling sentences. A good rule of thumb on sentence length is ‘No sentence should have more than 20 words’.
 
Now, like all rules, you may need to break this one; it’s more general guidance than a rule.
 
Simplex, complex and compound
Here’s a simple example:
The committee has approved the proposal.
The subject is ‘the committee’ and the predicate is ‘has approved the proposal’.
 
Now a more complex example:
The Finance Committee, which met on Monday 13 April 2015, has approved the proposal put forward by the HR Committee that apart from graduate recruitment, recruitment be frozen for the next two months.
The simple subject is ‘the finance committee’ and the simple predicate is ‘approved the proposal’.
 
Then there are complex subjects and predicates:
The committee and the board have discussed and approved the proposal.
Here there are two nouns in the subject (the committee and the board) and two verbs relating to that subject (discussed and approved).