大便时排出鲜血，肉眼见血与便不混，大便成形。应首选的检查是

A．大便常规镜检

B．肛门直肠指检及直肠镜检查

C．乙状结肠镜

D．纤维结肠镜

E．钡灌肠

Many of the activities performed during the preliminary investigation are still being conducted in（）, but in much greater depth than before. During this phase, the analyst must become fully aware of the（） and must develop enough knowledge about the （） and the existing systems to enable an effective solution to be proposed and implemented. Besides the（）for process and data of current system, the deliverable from this phase also includes the （） for the proposed system.

A．hardware and software specification

B．system performance specification

C．formal requirements definition

D．general problem statement