词汇与结构In the design of the cockpit in a military fast jet, the traditional “knobs and dials” associated with the cockpit are mainly _______.

Which of the following is NOT true of the alveolar sac A: Directly communicates with the alveolar duct B: Has an interrupted wall represented by knobs between adjacent alveoli C: The space surrounded and opened by many alveoli D: Connective tissue fibers encircle the openings of the alveoli E: Smooth muscle disappears in this segment

Which of the following is NOT true of the alveolar sac() A: Directly communicates with the alveolar duct B: Has an interrupted wall represented by knobs between adjacent<br/>alveoli C: The space surrounded and opened by many alveoli D: Connective tissue fibers encircle the openings of the alveoli E: Smooth muscle disappears in this segment