我国科技工作者已研制出预防“非典”的疫苗,并进入临床试验阶段。该疫苗在人体免疫中属于[ ]
A.抗原
B.抗体
C.病原体
D.非特异性免疫
答案:A
It was raining hard. Little Tom felt cold, so he stood______to his mother.
A.close
B.closely
C.closed
D.nearly
患者无痛性血尿,超声示膀胱三角区 * * 状隆起性病灶3cm×2cm,基底部较宽,不随体位移动,首选诊断是()
A.膀胱结石
B.膀胱内血凝块
C.血管瘤
D.膀胱癌
E.膀胱内异物