1. SENTENTIAL ERRORS IN WRITING
1 COMMA SPLİCE
2 RUN-ON SENTENCE
3 NON-PARALLEL SENTENCE
4 SENTENCE FRAGMENTS

2. COMMA SPLİCE
A comma splice is the use of a comma to join two independent clauses. For example:
It is nearly half past five, we cannot reach town before dark.[1]
Although acceptable in some languages and compulsory in others, comma splices are usually considered style errors in English.

3. CORRECTİON
Simply removing the comma does not correct the error, but results in a run-on sentence. There are several ways to correct a comma splice:
Change the comma to a semicolon, colon, or dash:
It is nearly half past five; we cannot reach town before dark.
We cannot reach town before dark: it is nearly half past five.
It is nearly half past five—we cannot reach town before dark.

4. CORRECTION Write the two clauses as two separate sentence:
It is nearly half past five. We cannot reach town before dark.
Insert a coordinating conjunction following the comma:
It is nearly half past five, and we cannot reach town before dark.
It is nearly half past five, so we cannot reach town before dark.
Make one clause dependent on the other:
Because it is nearly half past five, we cannot reach town before dark.
It is nearly half past five, which means we cannot reach town before dark.
Use a semicolon plus a conjunctive adverb:
It is nearly half past five; hence, we cannot reach town before dark.

5. RUN-ON SENTENCE
A run-on sentence is a sentence in which two or more independent clauses are joined without appropriate punctuation or conjunction. It is generally considered a stylistic error, though it is occasionally used in literature and may be used as a rhetorical device. An example of a run-on is a comma splice, in which two independent clauses are joined with a comma without an accompanying coordinating conjunction.Some prescriptivists  exclude comma splices from the definition of a run-on sentence,but this does not imply that they consider comma splices to be acceptable.

6. RUN-ON SENTENCE
The mere fact that a sentence is long does not make it a run-on sentence; sentences are run-ons only when they contain more than one independent clause. A run-on sentence can be as short as four words—for instance: I drive she walks. In this case there are two independent clauses: two subjects paired with two intransitive verbs. So as long as clauses are punctuated appropriately, a writer can assemble multiple independent clauses in a single sentence; in fact, a properly constructed sentence can be extended indefinitely.

7. EXAMPLE
A run-on sentence, without any punctuation or conjunction between "gas" and "we":
My car is out of gas we cannot reach town before dark.
A comma splice, which is considered a run-on sentence in English by some usage experts:
It is nearly half past five, we cannot reach town before dark.

8. REMEDİES
Use separate sentences. However, this may disconnect related independent clauses and cause some of the meaning to be lost:
It is nearly half past five. We cannot reach town before dark.
Use a semicolon. This maintains the connection between the clauses while ensuring a pause between the two ideas:
It is nearly half past five; we cannot reach town before dark.
Use a coordinating conjunction.
It is nearly half past five, so we cannot reach town before dark.

9. NON-PARALLEL SENTENCE
Understanding Parallel Structure
Parallel structure (also called parallelism) is the repetition of a chosen grammatical form within a sentence.By making each compared item or idea in your sentence follow the same grammatical pattern, you create a parallel construction.
Example
Not Parallel:
Ellen likes hiking, the rodeo, and to take afternoon naps.
Parallel:
Ellen likes hiking, attending the rodeo, and taking afternoon naps. OR
Ellen likes to hike, attend the rodeo, and take afternoon naps

10. NON-PARALLEL SENTENCE
Using Parallel Structure
With Coordinating Conjunctions
When you connect two or more clauses or phrases with coordinating conjunction (for, and, nor, but, or, yet, or so), use parallel structure.
Example
Not Parallel:
My best friend took me dancing and to a show.
Parallel:
My best friend took me to a dance and a show.
With Correlative Conjunctions
When you connect two clauses or phrases with a correlative conjunction (not only…but also, either…or,
neither…nor, if…then, etc.), use parallel structure.

11. EXAMPLE: Not Parallel:
My dog not only likes to play fetch, but also chase cars.
Parallel:
My dog not only likes to play fetch, but he also likes to chase cars. OR
My dog likes not only to play fetch, but also to chase cars.
With Phrases or Clauses of Comparison
When you connect two clauses or phrases with a word of comparison, such as than or as, use parallel structure.
Example
I would rather pay for my education than financial aid.
I would rather pay for my education than receive financial aid

12. EXAMPLE :
Some helpful hints on how to revise sentences for parallel structure:
1) Figure out what parts of the sentence are being compared.
2) Decide whether they are parallel, i.e. arranged or constructed in the same way.
3) If they are not, make them parallel by making the grammatical construction the same in each part.
Bruce Wayne enjoys donning his Batman costume, answering the Commissioner's phone calls, and saving
Gotham City from cruel villains like the Penguin.

13. SENTENCE FRAGMENTS
A SENTENCE FRAGMENT fails to be a sentence in the sense that it cannot stand by itself. It does not contain even one independent clause. There are several reasons why a group of words may seem to act like a sentence but not have the wherewithal to make it as a complete thought.
It may locate something in time and place with a prepositional phrase or a series of such phrases, but it's still lacking a proper subject-verb relationship within an independent clause:
EXAMPLE: In Japan, during the last war and just before the armistice.

14. This sentence accomplishes a great deal in terms of placing the reader in time and place, but there is no subject, no verb.
It describes something, but there is no subject-verb relationship:
EXAMPLE: Working far into the night in an effort to salvage her little boat.
This is a verbal phrase that wants to modify something, the real subject of the sentence (about to come up), probably the she who was working so hard.
It may have most of the makings of a sentence but still be missing an important part of a verb string:

15. EXAMPLE: Some of the students working in Professor Espinoza's laboratory last semester.
Remember that an -ing verb form without an auxiliary form to accompany it can never be a verb.
It may even have a subject-verb relationship, but it has been subordinated to another idea by a dependent word and so cannot stand by itself:
EXAMPLE: Even though he had the better arguments and was by far the more powerful speaker.
This sentence fragment has a subject, he, and two verbs, had and was, but it cannot stand by itself because of the dependent word (subordinating conjunction) even though.