The students _______ busily when Miss Brown went to get a book she _______ in the office.

A．had written; left

B．were writing; has left

C．had written; had left

D．were writing; had left

男，67岁，临床表现为尿频、尿急、尿流缓慢、尿流中断和排尿不尽。直肠指诊发现前列腺增大，质韧，边缘清楚，未触及不规则硬结。血清PSA为9ng／ml。

首选的影像学检查方法为（）

A.CT平扫

B.TRUS

C.MRI增强检查

D.腹部平片

E.经腹超声检查