Read and fill in the blanks（阅读短文，首字母填空）
The sea covers a great part of the Earth’s surface. It is the h【小题1】 of millions of living things. Do you know there is more life in the sea than on the l【小题2】 ? The animals and plants in the sea are very i【小题3】  to man as a resource of food. Today more and more people are studying the sea. This is because the population of the Earth is increasing so fast that the land will not be able to provide food f【小题4】 every day. And the sea can provide us with a lot of food and f【小题5】 water in the future.