Many of the activities performed during the preliminary investigation are still being conducted in (1) , but in much greater depth than before. During this phase, the analyst must become fully aware of the (2) and must develop enough knowledge about the (3) and the existing systems to enable an effective solution to be proposed and implementeD. Besides the (4) for process and data of current system, the deliverable from this phase also includes the (5) for the proposed system.

1（）

A．analysis phase

B．design phase

C．implementation phase

D．maintenance phase

标况下，将O₂和NO₂按1：4体积比充满一干燥烧瓶，把烧瓶立于水中，瓶内液面逐渐上升，最终充满整个烧瓶，则所得溶液的物质的量浓度为（　　）

A．

B．

C．

D．