Помогите номера 49 и 50.
49.
year- years
territory-territories
day-days
man-men
forest-forests
leaf-leaves
place-places
box-boxes
foot-feet
century-centuries
woman-women
child-children
50.
radiate-radiation
cultivate-cultivation
darken-darkness
develop-development
protect-protection
hold-holding
От слова hold можно образовать еще одно существительное - holder.