Passage Two

Questions 26 to 30 are based on the following passage.

Certain animals and plants develop characteristics(特性)that help them cope with their environment better than others of their kind. This natural biological process is called adaptation(适应性). 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 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 for adapting. They may adapt in their structure，function，and genetics(遗传素质)；in their development and production of the young；and in other respects. An organism may create its own 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.

 Some plants and animals develop superior characteristics so that they may______.