all of a sudden.......
I am partial to thinking of eureka as meaning "I have found it!" You could use the word, almost always with an exclamation mark, to indicate a sudden or particularly deep insight that solves a long standing problem.
Pest sentence
I am not familiar with the word 'taction'.
a good sentence is "I cannot use oversimplification in a sentence." that sentence is oversimplification.
a BRAIN is what you use to get a right answer
All of a sudden I found that I had written a sentence in reply to a question.
All of a sudden a wild badger attacked me.
The dean's sudden appearance in the room immediately rendered the entire class immobile.
The sudden loud noise was unnerving, causing everyone in the room to jump in surprise.
"Gale" means a strong gust of wind. So, an example sentence could be "A sudden gale ripped the papers out of my hand."
"He tried to grapple with the sudden realisation that he was alone in the world." "She grappled the ledge, clinging on for dear life."
Some elements have uncharacteristic nature.
I had a sudden whim to take a midnight walk.
Having such hot weather in winter was an abberation.
All of a sudden the group was enshrouded in the fog
''A sudden storm overtook us on our trip to Salinas"
I was momentarily taken aback by the kitten's sudden defiance.