These word combinations should never be used in formal writing.
What are contractions?
That is (there/their/they're) basketball.
That is their basketball.
Jen Mike and Susan decided to go for a run.
Jen, Mike, and Susan decided to go for a run.
OR
Jen, Mike and Susan decided to go for a run.
I cannot find the books
I cannot find the books.
This sentence exhibits the main point of an essay.
What is a thesis?
He has (a lot/alot) of action figures.
He has a lot of action figures.
Although it was very cold he loved his trip to the beach.
Although it was very cold, he loved his trip to the beach.
Greg has to do three things today mow the lawn take out the trash and do the dishes.
Greg has to do three things today: mow the lawn, take out the trash, and do the dishes.
These should not be used in formal writing because they are shortened versions of a word. (Examples: ad and kids)
What are abbreviations?
Chris (does'nt/doesn't) enjoy the outdoors.
Chris doesn't enjoy the outdoors.
The school always offered apples bananas and oranges for snack.
The school always offered apples, bananas, and oranges for snack.
OR
The school always offered apples, bananas and oranges for snack.
I don't like the heat in july, but i love the cold in january.
I don't like the heat in July, but I love the cold in January.
The four components of a paper heading.
What are Your Name, Professor's Name, Course, and Due Date?
Steve (has/have/had) two chickens (who/whom) require special attention due to illness.
Steve has two chickens who require special attention due to illness.
I said "The rain stopped."
I said, "The rain stopped."
I caught the football now I've got a broken leg.
I caught the football; now I've got a broken leg.
The act of using another's work as your own.
What is plagiarism?
You must (of/have) heard by now that (there/their/they're) are (to/too/two) many mosquitos this summer.
You must have heard by now that there are too many mosquitos this summer.
Craig Paige and Laura were twiddling their thumbs but the principal told them to stop.
Craig, Paige, and Laura were twiddling their thumbs, but the principal told them to stop.
OR
Craig, Paige and Laura were twiddling their thumbs, but the principal told them to stop.
todd and paul have been best friends since kindergarten, but paul is moving to ireland this summer
Todd and Paul have been best friends since kindergarten, but Paul is moving to Ireland this summer.