莪术的抗癌作用机制是()
A.抑制肿瘤细胞蛋白质合成
B.对癌细胞有直接杀灭作用
C.增加肿瘤组织血流量
D.抑制肿瘤细胞核酸合成
E.以上均不是
参考答案:B
Scope definition is ().
A.the process of developing a detailed project scope statement as the basis for future project decisions
B.determining the responses needed to perform project activities
C.analysis of activity sequence, duration, and resource requirements
D.a written statement identifying the quality standards relevant to the project
防止设备产生负压的操作步骤是什么?