人体内与呼吸有关的主要肌肉是（ ）
A．肋骨间的肌肉和膈肌
B．腹部肌肉
C．胸部的肌肉
D．背部肌肉
参与呼吸运动的肌肉主要有膈肌、肋骨之间的肌肉等呼吸肌．平静吸气时，肋间肌和膈肌收缩，引起胸腔前后、左右及上下径均增大，肺随之扩大，形成主动的吸气运动；当肋间外肌和膈肌舒张时，肋骨与胸骨因本身重力及弹性而回位，结果胸廓缩小，肺也随之回缩，形成被动的呼气运动．
故选：A
| 完形填空。 | ||||
| Once upon a time there lived an old man in a nice cottage with a large garden. The old man was seen 1 his flowers all the time. They were so well-tended that every passer-by could not but 2 for a glance. One day a young man went by the garden. He gazed at the splendid garden, 3 in admiration at the beauty of these sceneries. Then, suddenly he 4 the old gardener was blind. 5 , the young man asked, "Why are you busy tending these flowers every day which you can't 6 in fact?" The old man smiled and answered that "I can tell you 7 reasons. First I was a 8 when I was young, and I really like this job. Second, although I can't see these flowers, yet I can 9 them. Third, I can smell sweetness of them. As to the last one, that's 10 ." "Me? But you don't know me," responded the young man 11 . "Yeah, it's 12 that I don't know you. But I know everyone knows flowers and would never 13 them down. I know the beauty of my garden will get many people into a good 14 . In the meantime, it also 15 a chance to me to have a word with you here and to enjoy the happiness these flowers have brought us." The old man's 16 astonished me. The blind man grows flowers and 17 them as a link of minds so as to make 18 enjoy the sunshine in spring. Isn't it one kind of happiness? I believe every flower has 19 with which they can see the kindness of the man's heart. The blind man grows flowers in his heart. Though 20 to see the beauty of blossoming, he surely can hear the voice of it, I suppose. | ||||
|