debian 10 aptはソフトウェアをインストールできません

debosでdebian 10のファイルシステムを構築し、apt-getでソフトウェアをインストールする際に次のエラーが発生しました.

Err:1 https://mirrors.ustc.edu.cn/debian buster/main armhf libpci3 armhf 1:3.5.2-1
  Certificate verification failed: The certificate is NOT trusted. The certificate chain uses not yet valid certificate.  
Could not handshake: Error in the certificate verification. [IP: 202.141.176.110 443]
Err:2 https://mirrors.ustc.edu.cn/debian buster/main armhf pciutils armhf 1:3.5.2-1
  Certificate verification failed: The certificate is NOT trusted. The certificate chain uses not yet valid certificate. 
 Could not handshake: Error in the certificate verification. [IP: 202.141.176.110 443]
E: Failed to fetch https://mirrors.ustc.edu.cn/debian/pool/main/p/pciutils/libpci3_3.5.2-1_armhf.deb  Certificate verification failed: 
The certificate is NOT trusted. The certificate chain uses not yet valid certificate.  Could not handshake: Error in the certificate verification. [IP: 202.141.176.110 443]
E: Failed to fetch https://mirrors.ustc.edu.cn/debian/pool/main/p/pciutils/pciutils_3.5.2-1_armhf.deb  Certificate
 verification failed: The certificate is NOT trusted. The certificate chain uses not yet valid certificate.  Could not handshake: Error in the certificate 
verification. [IP: 202.141.176.110 443]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing

プロンプトに従ってapt-get updateを実行すると、次のエラーが発生します.

Ign:1 https://mirrors.ustc.edu.cn/debian buster InRelease
Err:2 https://mirrors.ustc.edu.cn/debian buster Release
  Certificate verification failed: The certificate is NOT trusted. 
The certificate chain uses not yet valid certificate.  Could not handshake: Error in the certificate verification. 
[IP: 202.141.176.110 443]
Reading package lists... Done                          
E: The repository 'https://mirrors.ustc.edu.cn/debian buster Release' no longer has a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

分析は証明書の誤りが利用できないので、システムの時間を見て、2019年で、1年以上遅くなって、そこでntpdateでシステムの時間を更新します

$ ntpdate        IP

apt-get installインストールソフトウェアを再使用すると、正常にインストールでき、問題が解決します.