纤维素性炎的发生病因有（）
A.白喉杆菌
B.痢疾杆菌
C.肺炎双球菌
D.脑膜炎双球菌
E.尿毒症
参考答案：A, B, C, E
____________ is hungry?[ ]
A. Who
B. What
C. Where
They took a hell of a risk and suffered a great deal but it______.
A．paid back
B．paid up
C．paid off
D．paid down
