Maybe like how what when or were.
He had an intense interest in the 'supernatural' elements of Macbeth, particularly witches and their prophecy. In fact, king James I wrote a book about the supernatural, so that is why he was particularly interested in that part.
A plural noun refers to more than one of something. Many singular nouns just need an S added at the end to make them plural (e.g., bee and bees).
