I'll go to the library as soon as I finish what I _____.[ ]

A. was doing

B. am doing

C. have done

D. had been doing

结肠癌最早出现的症状为：（）

A．腹部胀痛

B．排便习惯与粪便性状改变

C．腹部肿块

D．贫血、消瘦、乏力等全身症状

E．肠道梗阻