应激原（stressor）
参考答案：
凡是能够引起应激反应的各种因素皆可称为应激原。
He turned ________ ten years ago but later he became ________. [ ]
A. a teacher; a doctor
B. teacher; doctor
C. teacher; a doctor
D. a teacher; doctor
能防御外邪入侵的是（）
A．卫气
B．元气
C．清气
D．水气
E．谷气
