I.                Fill in the blank with a suitable word Man probably could not live without the help of animals. The role of animals in the balance of nature ranks as their (1)…………………… important service to man. Animals also serve man by (2) …………………...him with many foods and other useful products. Without animals, man would (3) …………………... no meat, milk, eggs, or honey, or wool, fur, or silk. For thousands of years, man has caused changes in the animal kingdom. He has tamed many kinds of animals and used (4) …………………... for food and clothing. He has killed or driven away animals that once attacked or interfered with his use of land. Today, he tries to protect many kinds of animals that are (5)…………………… danger of dying. Like man, most plants depend (6) …………………...animals for many of their basic needs. Without animals, many (7). …………………...could not easily reproduce. For example, many plants with flowers depend on bees and other insects to carry their pollen (8)…………………… plant to plant. Many oak trees from acorns that squirrels bury and then forget, or from .acorns that deer step on and push down into the soil. Birds often (9)…………………… from one place to another with seeds slinging to (10) …………………...feet.