He spoke in such a low voice that it was impossible to make out exactly ___ he was trying to say. [ ]

A. it was what that

B. what was it that

C. that what it was

D. what it was that

关于视觉诱发电位叙述错误的是（）

A.双眼的会聚发生于视觉皮层

B.皮质盲不会导致闪光视觉诱发电位反应

C.是在视觉刺激（通常为交替性黑白棋盘型）后产生的枕叶皮层电位

D.视觉诱发电位检查可以证实伴有或不伴有视神经炎的多发性硬化

E.压迫性视神经病可导致视觉诱发电位产生波形与波幅的异常