Two aliens come back to earth to check up on humans, who they once helped overcome global warming and general extinction of all life due to contamination, only to find out that some things may still need a change.
1995
1927
1971
2005
1977
1984
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2012
1992
1994
2022
2024
2017
1975
2015
2009
2011
2021
1990
