Answer:
-1,000, 27r^21, g^3h^30 and -1 are all perfect cubes, assuming two of the expressions are rewritten as described below.
Explanation:
-1,000 is the result of (-10)^3
Is 27r21 supposed to be 27r^21? If so, it is the cube of 3r^7
343p is not a perfect cube (there is no p^3 factor).
Is g3h30 supposed to be g^3h^30? If so, it is a perfect cube of gh^10
-1 is a perfect cube of -1