The Four Sentence Structures

Simple Sentences
A Simple Sentence contains one piece of information. It makes sense on its own. It has a subject, a verb and an object. It is also referred to as an independent clause because it stands by itself as a complete sentence.
For instance,
The bus was late. 
"the bus" =subject, "was"= verb   
            
Reetika changed  the venue of the meeting.
Dhruv did not like eating junk food.
Garima waited for the bus.
I looked for Alam and Jigar at the railway station.

• Compound Elements in Simple sentences

Subject                                                 Jatin and Meera took the bus.

Verb          
    The typist typed and designed the text.

Direct Object    
  These students made some models and a small machine.
He prepared lunch and dinner.

Predicate Adjective    
      She felt sad and disappointed.

Object of the Preposition  
          They ate at Sagar Ratna and Chokhi Dhani.

Compound Sentences

Compound sentences contain two independent clauses or complete sentences. These are connected with coordinating conjunctions. Coordinating conjunctions can be easily remembered with an acronym FANBOYS

For

And

Nor

But

Or

Yet

So

For instance,

Rachit played in the courtyard, and Teena read in the house. 

Garima waited for the bus but the bus was late.

I looked for Alam and Jigar at the railway station but could not find them.

Jatin and Meera took the bus before I arrived, so I did not see them at the bus stand.

He organized the icons by name; then, he refreshed the page.

Complex Sentences

Complex Sentences contain  subordinate (dependent) clauses and independent clauses. A subordinate (dependent) clause is a group of words that has a subject and a verb but does not express a complete thought. Dependent clauses begin with subordinating conjunctions. Some of the subordinating conjunctions are:

after

although

as 

because

before

even though

if

since

though

unless

until

when

whenever

whereas

wherever

while

A Complex Sentence joins an independent clause with one or more dependent clauses. We can begin complex sentences with the dependent clause, followed by the independent clause by using comma after the dependent clause. For example:

Because Alam and Jigar arrived at the railway station early, I did not see them at the station.

While she waited at the bus stop, Garima realized that the bus was late.

We can use independent clause first and then dependent clause in complex sentences but no comma is used then. For example:

I did not see them at the station because Alam and Jigar arrived at the railway station early.

Garima realized that the bus was late while she waited at the bus stop.

Stuti cried because a stranger snatched her bag.

They studied the phrasal verbs for many hours as they were so interesting.

Compound-Complex Sentences
Compound and Complex Sentences can be combined. A Compound-Complex sentence contains at least two independent clauses and at least one dependent clause.For example,

She completed  her assignment but she still needs to work on her summary section even though she finished poetry analysis course last semester.