每次ELISA.测定后，能判断本次实验正常的较全面因素是：（）A.阴阳性合符要求 B

下列分解因式正确的是（　　）

A．2x²-xy-x=2x（x-y-1）

B．-xy²+2xy-3y=-y（xy-2x-3）

C．x（x-y）-y（x-y）=（x-y）²

D．x²-x-3=x（x-1）-3

（）是大客户销售的目的。

A.赚取利润

B.降低库存

C.获取企业长期、持续的收益

D.取得市场的竞争优势

Information systems design is defined as those tasks that focus on the specification of a detailed computer-based solution. Typically, there are four systems design tasks for in-house development. 1)The first task is to specify (1), which defines the technologies to be used by one, more, or all information systems in terms of their data, processes, interfaces, and network components. This task is accomplished by analyzing the data models and process models that are initially created during requirements analysis. 2)The next systems design task is to develop the (2). The purpose of this task is to prepare technical design specifications for a database that will be adaptable to future requirements and expansion. 3)Once the database prototype has been built, the systems designer can work closely with system users to develop input, output and dialogue specifications. The (3) must be specified to ensure that the outputs are not lost, misrouted, misused, or incomplete. 4)The fourth design task involves packaging all the specifications from the previous design tasks into a set of specifications that will guide the (4) activities during the following phases of the systems development methodology. Finally, we should (5) and update the project plan accordingly. The key deliverable should include a detailed plan for the construction phase that should follow.

空白（1）处应选择（）

A.an application architecture

B.adistributed system

C.asystem scope

D.a system physical model

架空电力线路在哪些电杆处应标明相序标志？

线路工程中线测量中，中线里程不连续即称为中线断链。