— What's the matter?

— She caught _____ bad cold and had to stay in _____ bed.[ ]

A. the; the

B. a; the

C. a; a

D. a; 不填

中毒性菌痢的主要发病机制是()

A．体质异常

B．胃酸浓度降低

C．痢疾杆菌外毒素中毒

D．特殊菌型的痢疾杆菌，外毒素中毒

E．痢疾杆菌内毒素中毒