Explanation:

It's unfortunate that he died of cancer.
“By” is usually a preposition but sometimes acts as an adverb. It can be used in many ways, but today we will talk about four uses as a preposition and show you where it is placed in a sentence. Let's start with using “by” to show place or location. When we use "by" this way, it means "close to" "next to" or "beside."
'Of' is mostly used as a preposition, and therefore, should be used when a preposition is needed.
From can be used with the prepositions 'to' and 'until' to mark the beginning and ending point of time of an action or state. Generally, 'from...to' is used with past tenses, while 'from...until' is used when speaking about future actions.
"With" is used as accompanied by (another person or thing).