多选题

Gadget has-a Sprocket and Gadget has-...

Question

Gadget has-a Sprocket and Gadget has-a Spring and Gadget is-a Widget and Widget has-a
Sprocket 以下哪两段代码可以表示这个关系? (选择两项) (    )

A. class Widget { Sprocket s }
class Gadget extends Widget { Spring s }

C. class Widget { Sprocket s1 Spring s2 }
class Gadget extends Widget { }

D. class Gadget { Spring s }
class Widget extends Gadget{ Sprocket s }

B. class Widget { }
class Gadget extends Widget { Spring s1 Sprocket s2 }