math
posted by kikay .
give an example of a set which has just two elements; one element; no elements; an infinite number of elements.

Are you just looking for text examples?
2 elements {moons of mars} which are {phobos, diemos}
1 element {radio amateurs with the call sign JY1} {The late King Hussein of Jordan}
0 elements {female astronauts who have walked on the moon}
infinite number of elements {number of decimal places pi can be expressed to] 
thanks! i really appreciate it.;)