[单项选择]All living things need air to live. People need clean air to breathe. But sometimes people make the air dirty. They drive so many cars that the fumes from the cars pollute the air.
Fumes are made when gasoline is burned. The fumes that come out of cars, buses and trucks can pollute the air.
Environmental engineers are people who work to protect the environment. One of their jobs is to design or plan cars that will not pollute the air. Some time ago environmental engineers designed an object for cars that removes harmful pollution. Now cars are causing less pollution than they once did, because environmental engineers worked hard to protect the environment.
Which is not said that can pollute our air
A. Smoke from our homes. B. Smoke from buses. C. Smoke from trucks.

[单项选择]All living things need air to live. People need clean air to breathe. But sometimes people make the air dirty. They drive so many cars that the fumes from the cars pollute the air.
Fumes are made when gasoline is burned. The fumes that come out of cars, buses and trucks can pollute the air.
Environmental engineers are people who work to protect the environment. One of their jobs is to design or plan cars that will not pollute the air. Some time ago environmental engineers designed an object for cars that removes harmful pollution. Now cars are causing less pollution than they once did, because environmental engineers worked hard to protect the environment.
All living things need air ______.
A. to grow B. to produce fruits C. to breathe

[填空题]If there is no air, there (be)（）no living things on the earth.

[单项选择] Adaptation of Living Things Certain animals and plants develop characteristics that help them cope with their environment better than others of their kind. This natural biological process is called adaptation. Among the superior characteristics developed through adaptation are those that may help in getting food or shelter, in providing protection, and in producing and protecting the young. That results in the evolution of more and more organisms that are better fitted to their environments. Each living thing is adapted to its way of life in a general way, but each is adapted especially to its own distinct class. A plant, for example, depends upon its roots to fix itself firmly and to absorb water and inorganic chemicals. It depends upon its green leaves for using the sun’’s energy to make food from inorganic chemicals. These are general adaptations, common to most plants. In addition, there are special adaptations that only certain kinds of plant
A. contexts
B. surroundings
C. neighbors
D. enemies