— Listen! Helen is singing in the hall.

— It _____ be Helen. She has gone to Beijing. [ ]

A. can't

B. may

C. mustn't

D. should

关于急性播散性脑脊髓炎下列哪项描述不正确（）

A.是广泛累及脑和脊髓白质的急性炎症性脱髓鞘疾病

B.通常发生在感染后、出疹后或疫苗接种后

C.其病理特征为脱髓鞘病变常侵犯大脑半球或整个脑叶，病变多不对称，多以一侧枕叶为主

D.急性坏死性出血性脑脊髓炎又称为急性出血性白质脑炎

E.应与单纯疱疹病毒性脑炎和多发性硬化鉴别