【答案解析】
Environment is to us what water is to fish. It is so important to us that we should all take measures to protect it, because nobody can afford to lose the precious environment.
However, people take different attitudes towards environmental protection. Some people think that the environment belongs to us all, and that it is "our" business, and therefore, not mine. So they are not aware that they should take a part in the protection of the environment. This could be very dangerous if everybody holds such an irresponsible view. Fortunately, there are people who regard the protection of the environment as their own business. They do more than mere talk about the environment. For example, they avoid using plastic bags; they sort things out for recycling; and they volunteer to plant trees and grasses. It is these people that are preventing the environment from worsening, and are bringing hopes to ourselves and our future generations.
All in all, everybody's business shouldn't be nobody's business as regards to environment. All of us need to work hand in hand, and we can surely make the world a better place.