A.It cannot be created without a package specification.
B.It cannot invoke subprograms defined in other packages.
C.It can contain only the subprograms defined in the package specification.
D.It can be changed and recompiled without making the package specification invalid.来自 “ ITPUB博客 ” ,链接:https://blog.itpub.net/17013648/viewspace-1239849/ ,如需转载,请注明出处,否则将追究法律责任。