原发性肝癌的病因包括
A.病毒性肝炎
B.肝硬化
C.黄曲霉毒素
D.亚硝胺类
E.酒精
参考答案:A,B,C,D,E
All of a sudden, he rushed out of the room, ________never to come back again.[ ]
A. determine
B. to determine
C. determined
D. having determined
使用置换法时,不但要将容器内彻底置换,还必须注意清洗容器外部。