In my opinion, they do not only reveal what will happen, but also manipulate events. When Macbeth approached the witches, they could have concealed the truth from him and just let the events unfold, but they didn't do it. They told him about the prophecy, thus initiating the events that soon followed. If they hadn't told him the truth, Macbeth might have never killed Banquo, Duncan, and the rest in order to become king. So yes, they manipulated events and caused a great tragedy.
Answer:
A portion of a word that forms the base of a word is its Baseword
Prefix is a word, letter, or number placed before another.
suffix is a morpheme added at the end of a word to form a derivative.
