—He ____be in the classroom, I think.

—No, he_____ be in the classroom. I saw him go home a minute ago.

A．can, may not

B．must, may not

C．may, can’t

D．may, mustn’t

男性，65岁，左侧腹痛，腹泻半年，间断出现脓血便，查体：腹部未及包块。最合适的检查方法是（）

A.结肠镜检查

B.全胃肠钡透

C.腹部CT

D.结肠钡灌透视

E.便常规