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问题 解答题
化简：[
a2-b2
a2+2ab+b2
+
2
ab
÷（
1
a
+
1
b
）2]•
2
a2-b2+2ab
答案

原式=[

(a+b)(a-b)
(a+b)2
+
2
ab
×
a2b2
(a+b)2
]×
2
a2-b2+2ab

=[

a2-b2
(a+b)2
+
2ab
(a+b)2
]×
2
a2-b2+2ab

=

2
(a+b)2
．

故答案为

2
(a+b)2
．

填空题

《环境空气总烃的测定气相色谱法》（GB／T15263-1994）测定总烃时，若以氮气为载气，则总烃峰中包括氧组分，因样品中氧对响应值有效应，在此，采用除烃净化空气求出（）值，从总烃峰中扣除氧组分值。
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单项选择题

The Rational Unified Process (RUP) is a software engineering process, which captures many of best practices in modern software development. The notions of (21) and scenarios have been proven to be an excellent way to capture function requirements. RUP can be described in two dimensions - time and content. In the time dimension, the software lifecycle is broken into cycles. Each cycle is divided into four consecutive (22) which is concluded with a well-defined (23) and can be further broken down into (24) - a complete development loop resulting in a release of an executable product, a subset of the final product under development, which grows incrementally to become the final system. The content structure refers to the disciplines, which group (25) logically by nature.

A. rounds B. loops C. iterations D. circularities
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