Extreme Programming (XP) is a discipline of software development with (14) of simplicity, communication, feedback and courage. Successful software development is a teameffort - not just the development team, but the larger team consisting of customer,management and developers. XP is a simple process that brings these people together andhelps them to succeed together. XP is aimed primarily at object-oriented projects using teamsof a dozen or fewer programmers in one location. The principles of XP apply to any (15) project that needs to deliver quality software rapidly and flexibly.

An XP project needs a(an) (16) customer to provide guidance. Customers, programmers, managers, are all working (17) to build the system that’sneedeD． Customers - those who have software that needs to be developed - will learn simple,effective ways to (18) what they need, to be sure that they are getting what they need,and to steer the project to success.

（17）应选入（）。

A．together

B．by themselves

C．separately

D．alone

转化气中残余甲烷含量越高，说明（）

A、烃类的转化率越高

B、烃类的转化率越低

C、不反应烃类的转化率