The Rational Unified Process (RUP) is a software engineering process, which captures many of best practices in modem software development. The notions of use-cases and ______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 ______ which is concluded with a well-defined ______ and can be further broken down into ______ 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 ______ logically by nature.

A. aspects B. phases C. orientationsD. views

有效地利用现有能源和开发新能源是改变能源危机的有效措施，已受到各国的普遍重视。

(1)可用改进汽油组成的办法来改善汽油的燃烧性能。例如，加入CH₃OC(CH₃)₃来生产“无铅汽油”CH₃OC(CH₃)。分子中必存在的原子间连接形式有_________（填写编号）。 

(2)天然气的燃烧产物无毒、热值高，而且管道输送方便，将成为我国西部开发的重点项目之一。天然气常和石油伴生，其主要的成分是____。能说明它是正四面体而非正方形平面结构的理由是____（填写编号）。

①其一氯取代物不存在同分异构体

②其二氯取代物不存在同分异构体

③它是非极性分子

④它的键长和键角都相等

(3)1980年我国首次制得一辆燃烧氢气的汽车，乘员12 人，以50 km/h行驶了40 km。为了有效开展民用氢能源，首先必须制得廉价的氢气，下列可供开发较经济的制氢方法是 ____________（填写编号）；还需要进一步解决的问题是____________。

①电解水②锌和稀硫酸反应③光解海水