Exercise 4: Read the passage carefully and choose the correct answers. The natural environment includes all natural rescources that are necessary for life: the air, the oceans, the sun and the land. Because they are vital for life, these resources must be protected from pollution and conserved. Ecologists study their importance and how to use them carefully. According to ecologists, resources are divided into two groups: renewable and non-renewable. When a resource is used, it takes some time to replace it. If the resource can be replaced quickly and easily, it is called renewable. If it cannot be replaced quickly and easily, it is called non-renewable. For example, grass for animals is a renewable resource. When cows eat the grass, the resource is used. If the soil is fertilized and protected, more grass will grow. Coal, however, is non-renewable because it takes millions of years to make coal. All fossil fuels are non-renewable resources. 1. The natural environment consists of _________. A. the air and the land B. the oceans and the sun C. the sun and the land D. all natural resources 2. According to ecologists, there are _________ resource groups. A. two​​​B. three​​​C. four​​D. five 3. If the resource can be _________, it is called renewable. A. burnt quickly B. replaced quickly C. divided quickly D. used quickly 4. Grass for animals is a _________ resource. A. limited B. non-renewable C. renewable D. clean 5. According to the passage, coal is non-renewable because it takes _________ to make coal. A. hundreds of years B. thousands of years C. millions of years D. billions of years