小弟新人 ，直接运行本书中第13章Staff Manager 的源码，QT报错
D:\QtPro\qt-book\chap13\staffmanager\employeeform.h:4: error: QDialog: No such file or directory
#include <QDialog>
D:\QtPro\qt-book\chap13\staffmanager\employeeform.cpp:4: In file included from ..\staffmanager\employeeform.cpp:4:0:
什么原因啊，求解答，谢谢
