What are the 3 conditions that must exist when ent or ence added to end of words?

You're actually thinking about the suffixes "-ant" and "-ence", which are used to form nouns from verbs or adjectives. There's no specific set of "3 conditions" for their use, but here's a breakdown of how they work:

-ant

* Forms nouns that denote a person or thing that performs an action or has a quality:

* *Act* + ant = *Actor* (someone who acts)

* *Assist* + ant = *Assistant* (someone who assists)

* *Import* + ant = *Import*ant* (something that is important)

-ence

* Forms nouns that denote a state, quality, or action:

* *Exist* + ence = *Existence* (the state of being)

* *Confid* + ence = *Confidence* (the quality of being confident)

* *Resist* + ence = *Resistance* (the action of resisting)

Key Considerations:

* Word Root: The base word often determines the appropriate suffix. Look at the meaning of the base word to understand if it describes a person/thing performing an action, or a state/quality.

* Pronunciation: The ending "-ence" is usually pronounced as a soft "s" sound.

* Common Usage: Certain words are consistently used with one suffix or the other. This is where familiarity and practice come in.

Note: While these suffixes are often used to create nouns, there are exceptions. Some words can be both nouns and verbs. For example: "attendance" (noun) and "attend" (verb).

It's important to remember that these are general guidelines. There are always exceptions and nuances in language. If you are unsure, consult a dictionary or grammar resource.