He said that he ________ the novel and had not finished it yet.
A. had been writing
B. has written
C. writes
D. is writing
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The man ________ there in the sun for a long time and got his face burnt.
A. has stood
B. was standing
C. had been standing
D. is standing
在血清诊断试验中不同实验室或不同的仪器对同一未知样本做检测，目的是评价（ ）
A. 试验可靠性
B. 试验实用性
C. 试验真实性
D. 试验敏感性
E. 试验特异性
下列疾病适合做大规模筛检的是（ ）
A. 原位子宫颈癌
B. 全民检查HBsAg
C. 艾滋病
D. 流行性感冒
E. 麻疹
为了尽量发现病人,在制定诊断标准的过程中,常常需要( )
A. 提高特意度
B. 提高灵敏度
C. 降低假阳性率
D. 提高假阴性率
E. 使假阳性率与假阴性率相等
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