Certain animals and plants develop characteristics that help them deal 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 gradual development of more and more organisms（small living things）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 (kind ) . A plant, for example, depends upon its roots to fix itself firmly and to absorb water and inorganic chemicals (无机化学物). 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 plants have.

　　 Many animals have adaptations that help them escape from their enemies. Some insects are hidden by their body color or shape, and many look like a leaf or a little branch. The coats of deer are colored to mix with the surroundings. Many animals have the ability to remain completely still when an enemy is near.

　 Organisms have a great variety of ways of adapting. They may adapt in their structure, function, and genetics; in their development and production of the young; and in other respects. An organism may create its won environment, as do warm-blooded mammals, which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather. Usually adaptations are an advantage, but sometimes an organism is so well adapted to a particular environment that, if conditions change, it finds it difficult or impossible to readapt to the new conditions.

40. Some plants and animals develop superior characteristics so that they may　　　 .

　 A. help others of their kind get food, shelter and other things needed

　 B. survive even in extremely severe conditions

　 C. become better adapted to the environments than others of their kind

　 D. result in the evolution and production of more intelligent organisms

41. In the first paragraph, the word "environments" could best be replaced by 　　　 .

　 A. contexts　　　 B. surroundings　　　　　 C. neighbors　　　 D. enemies

42. It can be inferred from this passage that the feathers of a bird are colored 　　　 .

　 A. to frightened its enemies.　　　　　　　 B. to attract its enemies

　 C. to adjust its body heat　　　　　　 D. to match its environment

43. Which of the following is not directly mentioned?

　 A. A living thing may adapt in its structure.

　 B. An organism may adapt in its function.

　 C. A living creature may adapt in its genetic makeup.

　 D. A living organism may adapt in its sleeping habit.