For the transfer function of all-pass systems, which of the following statements are correct?
选项：

A:All-pass systems can be used to assist the implementation of a stable system.;
B:All-pass systems can be used to assist the implementation of a linear-phase system.;
C:All-pass systems can be used to assist the implementation of a minimum phase delay system in a certain magnitude characteristic.;
D:All-pass systems can be used to assist the implementation of a bounded system.