Answer:
Holes.
Slant asymptote.
Explanation:
The terms holes when we talk about rational function, refers to a point that represents a discontinuity, that is, the point is not part of the function, it's undetermined, that's why is called a hole, because the graph of the rational function can be drawn perfectly, but at some point the function jumps over a "hole". Specifically, these "holes" tend to be just a point of discontinuation, and the graph continues its course.
On the other hand, slant slope asymptotes refers to oblique asymptotes.
Asymptotes also represent a discontinuation of the function when some element of the domain is undetermined, that is, when some x-value give 0/0 as a result, which cannot be determined. For example, if a rational function is undetermined at x = 1, that means x = 1, represents an asymptote, which is a not-solid line through which the function cannot past. So, in this case we are talking about oblique asymptotes, that what means "slant asymptote".
So, as you can see, these two terms are key feature of a rational functions, because they defines the function as such.