228. Oh, the classroom is so dirty. It needs ______ before we begin our class.

A．cleaned

B．being cleaned

C．to clean

D．Cleaning

再生障碍性贫血的口腔表征是（）

A.口腔黏膜苍白色，以唇、舌、龈明显

B.舌背黏膜广泛发红，呈鲜牛肉色

C.口腔黏膜苍白，并可出现瘀点、瘀斑或血肿

D.牙龈明显增生、肥大、水肿

E.牙龈炎，牙龈自发性出血