[系分] 包图

绘图要点：

要写具体的东西

UI：涉及的页面
controller：按照规程，类图的第一层
domain layer / model：背单词涉及的单词

foundation：外部设备 (有时可省略)

例子：

For OO architecture design, we always use MVC pattern to build layer architecture. Develop a
package diagram illustrates these layers. Please show the dependencies between packages, and
then put software classes of the main scenario of the use case“背单词”into these packages.