Debian 更新 update 出现 没有公钥 的解决办法

情况如题，命令及信息(关键处我换成了**)如下

apt-get update
Get:1 http://security.debian.org wheezy/updates Release.gpg [1554 B]
Get:2 http://security.debian.org wheezy/updates Release [39.0 kB]
Get:3 http://ftp.debian.org wheezy Release.gpg [2373 B]
Get:4 http://security.debian.org wheezy/updates/main amd64 Packages [414 kB]
Get:5 http://ftp.debian.org wheezy Release [191 kB]      
Get:6 http://security.debian.org wheezy/updates/contrib amd64 Packages [14 B]  
Get:7 http://security.debian.org wheezy/updates/non-free amd64 Packages [14 B] 
Get:8 http://security.debian.org wheezy/updates/main i386 Packages [416 kB]   
Get:9 http://ftp.debian.org wheezy/main amd64 Packages [5839 kB]       
Get:10 http://security.debian.org wheezy/updates/contrib i386 Packages [14 B]  
Get:11 http://security.debian.org wheezy/updates/non-free i386 Packages [14 B]  
Get:12 http://security.debian.org wheezy/updates/contrib Translation-en [14 B]  
Get:13 http://security.debian.org wheezy/updates/main Translation-en [227 kB]         
Get:14 http://security.debian.org wheezy/updates/non-free Translation-en [14 B]       
Get:15 http://ftp.debian.org wheezy/contrib amd64 Packages [42.0 kB]
Get:16 http://ftp.debian.org wheezy/non-free amd64 Packages [80.8 kB]
Get:17 http://ftp.debian.org wheezy/main i386 Packages [5857 kB]
Get:18 http://ftp.debian.org wheezy/contrib i386 Packages [42.3 kB]                                                                                                                           
Get:19 http://ftp.debian.org wheezy/non-free i386 Packages [77.6 kB]                                                                                                                          
Get:20 http://ftp.debian.org wheezy/contrib Translation-en [34.8 kB]                                                                                                                          
Get:21 http://ftp.debian.org wheezy/main Translation-en [3846 kB]                                                                                                                             
Get:22 http://ftp.debian.org wheezy/non-free Translation-en [66.1 kB]                                                                                                                         
Fetched 17.2 MB in 11s (1444 kB/s)                                                                                                                                                            
Reading package lists... Done
W: There is no public key available for the following key IDs:
9D6D8F6BC857**06
W: There is no public key available for the following key IDs:
7638D0442B90**10

解决命令，我是单条输入，应该可以多条同时输入

root@localhost:~# sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 9D6D8F6BC857**06
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.mZzL1FD9Mr --trustdb-name /etc/apt//trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-jessie-stable.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-squeeze-automatic.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-squeeze-stable.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-wheezy-automatic.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-wheezy-stable.gpg --recv-keys --keyserver keyserver.ubuntu.com 9D6D8F6BC857C906
gpg: requesting key C857C906 from hkp server keyserver.ubuntu.com
gpg: key C857C906: public key "Debian Security Archive Automatic Signing Key (8/jessie) <ftpmaster@debian.org>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)

root@localhost:~# sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 7638D0442B90<span style="font-family: Arial, Helvetica, sans-serif;">**</span><span style="font-family: Arial, Helvetica, sans-serif;">10</span>
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.rt1g675do6 --trustdb-name /etc/apt//trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-jessie-stable.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-squeeze-automatic.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-squeeze-stable.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-wheezy-automatic.gpg --keyring /etc/apt/trusted.gpg.d//debian-archive-wheezy-stable.gpg --recv-keys --keyserver keyserver.ubuntu.com 7638D0442B90D010
gpg: requesting key 2B90D010 from hkp server keyserver.ubuntu.com
gpg: key 2B90D010: public key "Debian Archive Automatic Signing Key (8/jessie) <ftpmaster@debian.org>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)