有机磷农药中毒患者的全血胆碱酯酶活性下降至正常人的______以下，对诊断有重要价值。
参考答案：80%
I Believe I Can Fly is a nice song by R. Kelly. This song tells us that believing in is very important.
A. themselves B. ourselves C. itself
全国计量工作的统一监督管理由
A．红色色标B．黄色色标C．绿色色标D．蓝色色标E．规定标志
