Simple Sentences:
* He was careless with his belongings and lost his keys.
* The careless driver caused a multi-car accident.
* Her careless words hurt her friend's feelings.
Sentences with Modifiers:
* The incredibly careless student forgot to turn in their assignment.
* The deliberately careless employee sabotaged the project.
* She was so careless with her phone that she dropped it in the toilet.
Sentences with Connotation:
* His careless attitude towards safety made his coworkers nervous.
* The careless handling of the chemicals resulted in a dangerous spill.
* The careless construction of the building led to its collapse.
Figurative Language:
* The careless words were like daggers piercing her heart.
* His careless actions left a trail of destruction in their wake.
* The careless disregard for the environment was a sign of our times.
Remember: The best sentence for "careless" depends on the specific context and the message you want to convey. Choose the sentence that best fits your needs!