Here's why:
* Not all verbs form nouns with "-ion": Many verbs don't have noun forms ending in "-ion." For example, "run," "eat," "sleep," "jump," etc.
* Spelling variations: Even when a verb forms a noun with "-ion," the spelling might change. For example, "create" becomes "creation," and "act" becomes "action."
* Meaning and usage: Some "-ion" nouns have specific meanings that don't directly relate to the verb. For example, "decision" is a noun, but it doesn't simply mean "the act of deciding."
Here are some examples:
* Verb: Sing - Noun: Song (not sing-ion)
* Verb: Walk - Noun: Walk (not walk-ion)
* Verb: Think - Noun: Thought (not think-ion)
However, here are some examples of verbs that DO form nouns with "-ion":
* Verb: Act - Noun: Action
* Verb: Reflect - Noun: Reflection
* Verb: Operate - Noun: Operation
It's important to consult a dictionary or thesaurus to find the correct noun form for a particular verb.