A requirement is simply a statement of what the system must do or what characteristics it needs to have. Requirements written from the perspective of user and focus on user needs are called (1). Requirements written from the developer's perspective and describe how the system will be implemented are called (2). Requirements evolve from detailed statements of the business capabilities that a system should have to detailed statements of the technical way in wluch the capabilities will be implemented in the new system. Requirements can be either functional or nonfunctional in nature. For example, during the analysis phase of travel vehicles sales system, the system that must have the ability to search for available inventory is (3). The requirement that the system should be able to work on any Web browser belongs to (4). That customer personal information is protected in compliance with the Data Protection Act is a requirement of (5).

空白（2）处应选择（）

A.operationalrequirements

B.businessrequirements

C.technical requirements

D.system requirements

甲公司准备为乙公司作中介寻找开发某商场的合作伙伴。两个公司签订了意向书，约定乙公司交付5万元定金作为与甲公司签订正式合同的担保。乙公司交付定金后，却委托另一家公司作中介，同时要求甲公司退还定金。对此要求： ( )。

A．甲公司应该退还，因为主合同没有成立，定金条款也无效

B．应该退还，因为乙公司没有构成根本违约，不能适用定金罚则

C．不予退还，因为乙公司根本违约，适用定金罚则

D．不予退还，此定金是立约定金，担保主合，同的签订