How well does the writer of "The Canterville Ghost" portray fear, mystery, suspense, and supernatural happenings in the story?
Ultimately, this is a question of opinion. Different readers will determine different levels of effectiveness across those four items. For me, when I look at all four of those items listed, I feel that the author does a mediocre job of portraying those elements. I think that Wilde does a great job of portraying supernatural happenings and mystery. The supernatural element is easy. The story is about an actual ghost, a reoccurring blood stain, and a "Garden of Death" that is accessed through a wall. The mystery of the story is done quite well too. The circumstances surrounding the house and why a ghost is there in the first place is mysterious. There is an element of mystery regarding how the ghost is going to try and scare the Otis family next, and there is an element of mystery regarding how the Otis family is going to annoy Sir Simon next.
However, I don't believe that Wilde portrays fear and suspense quite as well as the other two. Don't get me wrong, there are parts that are definitely scary. For example, the first time that Sir Simon tries to scare Mr. Otis is scary. The ghost shows up with burning red eyes, looking ragged, and dragging chains. That's scary. Unfortunately, Mr. Otis is not scared at all. His family isn't scared either. In fact, the Otis family makes it a goal to pester the ghost. They have fun with it. The fact that the Otis family isn't scared at all takes a great deal of potential fear and suspense out of the story. Readers know that the ghost is going to try all kinds of scary things, but we also know that none of it is likely to work. The story just isn't that terribly scary and suspenseful because of Wilde's intentional comedic elements.