若想检验某天然水是硬水还是软水，采用的方法是加入 （　　）

A．食盐水

B．肥皂水

C．石灰水

D．自来水

______ is the process of monitoring the status of the project and product scope and managing changes to the scope baseline. The key benefit of this process is that it allows the scope baseline to be maintained throughout the project.

A．Collect Requirements
B．Validate Scope
C．Control Scope
D．Create WBS