If I have a person element with a single gender, a single address, and a single gpa as children, which of the following would you put in the DTD to specify that gpa is optional?( )
(gpa*)
(gpa # REQUIRED)
(gpa?)
(gpa +)
青云测评
青云测评
If I have a person element with a single gender, a single address, and a single gpa as children, which of the following would you put in the DTD to specify that gpa is optional?( )
(gpa*)
(gpa # REQUIRED)
(gpa?)
(gpa +)
