Hi, I have read a sentence like this: Letting people know of the damage their negligence causes is responsible behavior. I wonder about the use of "of". I am more familiar with the sentence without "of", such as: Letting people know the damage their negligence causes is responsible behavior. My question is, why of is used in the sentence? I suspect maybe it's something connected with "causes", but I have never read anything like something causes of something, while cause here is a verb. Can someone help me clarify this usage of "of"? Thank you!