哮证发作的病因病机关键是
A．宿痰内伏于肺
B．外邪侵袭，触动伏痰
C．痰气相激，气道被阻
D．邪客于肺，气道不利
E．脏腑虚弱，气失所主
参考答案：B
A number of students_____ playing on the ground but I don't know what the exact number______.
[ ]
A. are; is
B. are; are
C. is; is
D. is; are
最可能的诊断是
A．房间隔缺损B．室间隔缺损C．动脉导管未闭D．法洛四联症E．病毒性心肌炎
