One child - Many children
One man - Many men
One house - Many houses
One country - Many countries
One woman - Many Women
One fish - не имеет мн. числа, кроме случая, когда речь идет о разных видах и сортах рыбы - fishes
One tooth - Many teeth
One sheep - не имеет мн. числа
One mouse - Many mice
One apple tree - Many apple trees
One town - Many towns
One fox - Many foxes
One city - Many cities
One shelf - Many shelves