Tpo24阅读分析(8)

般我们说显著的变化，所以答案A，其他答案都不准确

(5)

paragraph1: Of all the physiological differences in human sleep compared with wakefulness that have been discovered in the last decade, changes in respiratory control are most dramatic. Not only are there differences in the level of the functioning of respiratory systems, there are even changes in how they function. Movements of the rib cage for breathing are reduced during sleep, making the contractions of the diaphragm more important. [■] Yet because of the physics of lying down, the stomach applies weight against the diaphragm and makes it more difficult for the diaphragm to do its job. [■] However, there are many other changes that affect respiration when asleep. paragraph2: [■] To better understand breathing during sleep, it is, however, helpful to first understand how respiration works in general. During wakefulness, breathing is controlled by two interacting systems. [■]The first is an automatic, metabolic system whose control is centered in the brain stem. It subconsciously adjusts breathing rate and depth in order to regulate the levels of carbon dioxide (CO2) and oxygen (O2), and the acid-base ratio in the blood. The second system is the voluntary, behavioral system. Its control center is based in the forebrain, and it regulates breathing for use in speech, singing, sighing, and so on. It is capable of ignoring or overriding the automatic, metabolic system and produces an irregular pattern of breathing.

12. Look at the four squares [■] that indicate where the following sentence could be added

to the passage.