气厥实证反复发作的原因，常是（）
A．精神刺激
B．头部外伤
C．嗜食肥甘
D．思虑过度
E．先天禀赋
参考答案：A
求
You have walked such a long way on such a hot day. You __________ be tired and thirsty.[ ]
A. can
B. must
C. may
D. should
