—Alison, I'm sorry. I can't come to the wedding with you tomorrow morning.

—________?

—My grandma was severely ill, so I have to stay in the hospital to look after her.[ ]

A. How is it  

B. How come

C. So what  

D. What's the problem

对于伤寒杆菌，下列哪项错误（）

A.菌体裂解产生内毒素

B.属于肠道杆菌沙门菌属D群

C.革兰染色阴性

D.对一般化学药品不敏感

E.能耐低温