英文 careless vs carelessness

careless 是形容詞
carelessness 是名詞

雖然意思上好像都是"不小心"，但是配合寫法/作文/句子的結構便不會誤用，假如你需要用中文都"想像"用法，careless是形容某人的"不小心"+寫出是甚麼行為/做法，carelessness是某人的"不小心"本身
例如兩句同類意思的句意怎樣用這兩詞不同地寫
She is careless and caused the accident.她不小心而導致意外發生
Her carelessness was the cause of the accident. 她的不小心導玫意外發生

比較常見的寫法結構
She is a careless person, so she makes many mistakes.
Her carelessness makes her a fool all the time.