()是指强调实体的本质、内在的属性。在系统开发中,它指的是在决定如何实现对象之前的对象的意义和行为。
A.抽象
B.封装
C.信息隐藏
D.继承
参考答案:A
—Who's that under the tree? Is it Jenny?
—It _______ be Jenny. She's ill in hospital today. [ ]
A. can't
B. must
C. may
D. mustn't
近后备保护