everyone vs. every one

"Everyone" is use as a pronoun to mean all the people, or all the people in a group. But "every one" is used as an adverb to indicate each person.

Example:

Everyone must avoid common mistakes presented in the topics of "Common Mistakes in English Writing".

Every one of the students was interested in the topics of "Common Mistakes in English Writing".

in to vs. into

"into" is a preposition used as a function word:

1 - to indicate entry, introduction, insertion, superposition, or inclusion

Example: I came into the house.

2 - to the state, condition, or form of

Example: She got into trouble.

3 - to the occupation, action, possession of, involved with, or interested in

Example: I will go into farming.

4 - to indicate a period of time or an extent of space part of which is passed or occupied

Example: I took far into the night.

5 - in the direction of

Example: She was looking into the sun.

6 - to a position of contact with; against

Example: The car ran into a wall.

However, "into" cannot be used for "in to"!

Example:

She turned her paper into her teacher. (INCORRECT)

She turned her paper in to her teacher. (CORRECT)

See the following partitioning to understand why:

She turned ... in.

She turned her paper in.

To her teacher.

"She turned her paper in" + "To her teacher"

She turned her paper in to her teacher.

everyday vs. every day

Everyday is an adjective that means daily, commonplace, routinely, typically, or ordinary.

Example:

I go to an everyday class.

But every day is an adverb; a time expression meaning each day, or regularly.

Example:

I go to school every day.