软件的分层式体系结构把软件系统划分为4层，这4层结构自顶向下分别是______。
A．应用软件→业务构件→中间件→系统软件
B．业务构件→应用软件→中间件→系统软件
C．应用软件→中间件→系统软件→业务构件
D．业务构件→中间件→应用软件→系统软件
参考答案：A
解析： 软件的分层式体系结构是按层次组织软件结构的一种方法，每一层是通用性相同的一组子系统，低层的软件比高层的软件具有更高的通用性。
该分层式体系结构自顶向下分别是：应用软件层、业务构件层、中间件层、系统软件层。其中，应用软件层包括诸多应用系统，每个应用系统面向用户提供一组使用案例。业务构件层包括专门针对特定领域、特定业务类型的一系列构件系统，其所提供的使用案例和对象构件均是可复用的。中间件层提供不依赖平台的低层构件服务。系统软件层包括特定的平台软件和计算机网络基础设施等。
| Choose the best topic from A to F according to the meaning of each paragraph. | |
| International travelers, whether traveling for business or pleasure, will find themselves alone from time to time. Here are a few ways to meet new people and perhaps even get new travel chances. ( )1. Be polite and friendly. Remember to put yourself in social situations. Restaurants, shops and parks are all great places to meet people. If you want to make local friends in a country, stay near the places the locals often visit. ( )2. Keep a small photo album in your bag when you travel. Photos of family, friends and pets will help your new friends learn more about you. They will share their similar experiences with you, and it will help you learn more about your new friends. ( )3. Can you help your new friends improve their Chinese? Can you cook a traditional Chinese meal? By sharing your experiences, you can have a close relationship with your new friends that they won't soon forget. ( )4. Many foreigners love Chinese goods but have to pay a lot when buying them in their homeland, so you'd better prepare some gifts such as silks, tea and china (瓷器). They are always popular. ( )5. If you and your new friends get along well, you can give them your information and plan to live in each other's house for your next trip. Then you can visit their countries and stay in their houses while they stay in yours. In this way you will improve your friendship and live like a local abroad, but pay less for traveling. | |
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