— There _____ be anybody in the classroom, for the lights are off.

— I'll go and check. [ ]

A. mustn't

B. won't

C. needn't

D. can't

雷尼替丁治疗十二指肠溃疡的作用机制是

A．中和胃酸

B．直接抑制胃蛋白酶活性

C．阻断胃腺细胞的H₂受体，抑制胃酸分泌

D．形成保护膜，覆盖溃疡面

E．加速胃蛋白酶的分解