Find the general word:
1. water, earth, air, animals, nature
2. sea, stream, ocean, water, river, lake
3. a cow, a goat, animal, a sheep, a camel
4. a swallow, a parrot, a bird, an eagle, a crane, an owl, a dove
5. a fly, a flee, a bee, an insect, a dragon-fly, a grasshopper, a worm