The graph of a line and an exponential function can intersect twice, once, or not at all. Describe the possible number of intersections for each of the following pairs of graphs. Your solution to each part should include sketches of all the possibilities.

1. A line and a parabola

2. Two different parabolas

3. A parabola and a circle

4. A parabola and the hyperbola $y=\frac { 1 } { x }$