He is only too ready to help others, seldom, ______, refusing them when they turn to him.

A．if never

B．if ever

C．if not

D．if anything

MRI检查中TWI上呈不均匀高信号，下列哪种病变增强检查时有明显强化()

A．膀胱平滑肌瘤

B．膀胱憩室

C．膀胱癌

D．膀胱嗜铬细胞瘤

E．输尿管囊肿