What are the correct singular and plural possessive forms for each word?
Usually to make a word possessive you simply add 's
This works for all the singular words, however with the plural words the majority will, predictably, end up ending in 's'. In this case you simply have to add the apostrophe after the 's' (e.g. autumns --> autumns')
the only one exception in your list was 'child', as this has an irregular pluran - children.
Since this doesn't end in an 's', it is as simple as again adding 's