有关细菌性痢疾下列哪项是错误的

A．菌痢常见致病菌为福氏痢疾杆菌，宋内氏次之

B．“依链”痢疾杆菌活菌苗可用作人工主动免疫

C．菌痢是属于侵袭性腹泻

D．所有的痢疾杆菌只有内毒素

E．菌痢主要病变部位是直肠，乙状结肠

It has been announced recently that all the schools________ not have the students attend school if the

students have high temperatures.[ ]

A. need  

B. shall  

C. could  

D. ought to