关于支气管哮喘的描述正确的是
A.气道处于高反应状态
B.与变态反应原有关
C.气道慢反应炎症是基础病变
D.不可逆的气道阻塞性疾病
E.大多数3岁前起病
参考答案:A,B,C,E
Dr. Smith, together with his wife and daughters, ________ visit Beijing this summer.[ ]
A. is going to
B. are going to
C. was going to
D. were going to
气体继电器及其二次回路试验时,整定值符合运行规程要求,动作正确,绝缘电阻一般不低于()。
A.0.5MΩ
B.1MΩ
C.1.5MΩ
D.2MΩ