You should______. It's bad for your health.[ ]

A. stop smoking        

B. stop to smoke            

C. stopped smoking      

D. stop and smoke

诊断直肠癌最简单、方便的检查方法是（）.

A.大便常规化验

B.钡剂灌肠检查

C.直肠指检

D.乙状结肠镜检

E.粪便潜血试验