第3题: [单项选择]下列关于平静呼吸的描述,错误的是 A. 吸气时肋间外肌收缩 B. 吸气时膈肌收缩 C. 呼气时呼气肌收缩 D. 呼气时膈肌舒张 E. 呼气时肋间外肌舒张 参考答案:C
第4题:[单选题] Not until he retired from teaching three years ago ________ having holiday abroad. A. he had considered B. had he considered C. he considered D. did he consider 参考答案:D