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问题 单项选择题

已知某等差数列共有10项，其奇数项之和为15，偶数项之和为30，则其公差为（）。

A．5

B．4

C．3

D．2

答案

参考答案：C

解析：

a10-a9+a8-a7+a6-a5+a4-a3+a2-a1=5d-30-15d=3，选C。

单项选择题

进行故障诊断的先决条件是及时而正确地掌握()。

A．载荷向量

B．模型向量

C．状态向量

D．异常向量
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单项选择题

Ravi, like many project (126) , had studied the waterfall model of software development as the primary software life-cycle (127) . He was all set to use it for an upcoming project, his first assignment. However, Ravi found that the waterfall model could not be used because the customer wanted the software delivered in stages, something that implied that the system had to be delivered and built in (128) and not as (129) .
The situation in many other projects is not very different. The real world rarely presents a problem in which a standard process, or the process used in a previous project, is the best choice. To be the most suitable, an existing process must be (130) to the new problem. A development process, even after tailoring, generally cannot handle change requests. To accommodate change requests without losing control of the project, you must supplement the development process with a requirement change management process.

A．activity

B．procedure

C．process

D．progress
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