39.
It
can be concluded from the passage that in the used car market,
.
A.
used cars are generally cheap
B. used cars are actually expensive
C.
used cars are actually brand new
D. car
buyers are willing to pay a high price for a used car
B
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.