呼吸机使用不当,发生过度通气时,可出现哪些变化()
A.呼吸性碱中毒
B.氧离曲线向右偏移
C.加重组织缺氧
D.血pH下降
E.以上都是
参考答案:A, C
能影响血清抗体效价的主要因素有
A.年龄
B.体重
C.体质
D.有无进食
E.抗性药物的使用
Not until he called the secretary three times ______ that the manager went to an important meeting. [ ]
A. did he tell
B. he told
C. was he told
D. he was told