[系分] 包圖

繪圖要點：

要寫具體的東西

UI：涉及的頁面
controller：按照規程，類圖的第一層
domain layer / model：背單詞涉及的單詞

foundation：外部設備 (有時可省略)

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“背單詞”into these packages.