—Have you decided where to go for your summer vacation?

—Not yet. We _______ go to Qingdao. It is a good place for vacation. [ ]

A. may

B. should

C. need

D. must

细菌产生耐药性的机制包括（）

A.产生某种水解酶

B.产生某种钝化酶

C.改变胞质膜通透性

D.菌体内药用部位结构发生改变

E.细胞壁通透性改变