测定甲醛的水样采集后应尽快送实验室分析,否则需在每升样品中加入lml浓硫酸(特殊样品除外),使样品的pH≤(),并在24h内分析。
A.4
B.3
C.2
D.1
参考答案:C
急性乳腺炎形成脓肿后切开引流,下列哪项是错误的
A.切口应按放射方向
B.切口应引流通畅
C.必要时作对口引流
D.不要分离脓肿隔膜,以防扩散
E. * * 后脓肿可做弧形切口
---Did you listen to the speech?
--- No, we ______ it. But we had a lot of traffic on our way.
A.could have attended
B.must have attended
C.could attend
D.shouldn't have attended