C ++ is on the way 1

I started learning CPP today. This series is a summary of small problems encountered during the self-study process. the textbooks used are <C ++ in Action>

Question 1: expected unqualified-id before 'using'

Generally, it is caused by no extra points after the class declaration.

When the class is declared, there is no extra score, and an error may occur-error: a declaration specifies multiple types

Question 2: Does the data member in the class initialize according to the initialization sequence of the leading function?

Data members initialize according to the sequence they appear in the class definition.

Question 3: What is the sequence in which the inheritance class is constructed and destructed?

During the construction, the structure starts from the base class, and the hierarchy starts from the subclass at the highest level during the analysis. The process is the opposite.