So difficult _______it to work out the problem that I decided to ask Tom for some advice.

A．I did find

B．did I find

C．I’ve found

D．have I found

某男，25岁，淋巴结肿大6个月，一般治疗无效，肌肉疼痛，周期性发热。查体：腋下淋巴结肿大，对称，可活动，有弹性，大小为1．0cm，无压痛及触痛。有不洁性交史。为明确诊断应予以何种检查（）

A.血常规

B.便常规

C.抗-HIV检测

D.血培养

E.细胞免疫学检测