第 16 至 20 題為題組
         Goose bumps are one of those fight-or-flight reactions of the sympathetic nervous system. When youexperience cold or fear, a nerve reaction is sent to the muscles, which then contract involuntarily. Thismuscle contraction causes your body hair to stand erect. The skin with standing body hair __16__ agoose’s skin after its feathers have been plucked—hence the name goose bumps.
          But __17__ is this helpful to us as a response to fear or cold? Back in the days when our ancestorsmay have had a lot more body hair, this might have helped to keep them warm or scare an oncomingpredator. These days, however, goose bumps are __18__ to human beings. Goose bumps, or the reflexthat causes them, also occur in many other mammals. Many mammals fluff up their fur when __19__ , tolook bigger and thus more dangerous. For example, when a porcupine encounters a predator, its long sharppointed hairs will stand up as a means of __20__ . In animals with a thick hair coat, the rising of hair trapsmore air between the hairs, providing another layer of insulation to keep them warm.
【題組】16.
(A) imitates
(B) explains
(C) develops
(D) resembles