无法在BeagleBoneBlack（revC）上安装python3

BeagleBoneBlack revC装有Python2。但是我们需要运行Python3。

但是，尝试使用apt-get安装python3失败。似乎尝试安装下载站点上不存在的3.2版（请参阅http://ftp.us.debian.org/debian/pool/main/p/python3-defaults/）

root@beaglebone:~# sudo apt-get install python3 -V
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
   python3-minimal (3.2.3-6)
   python3.2 (3.2.3-7+deb7u1)
   python3.2-minimal (3.2.3-7+deb7u1)
Suggested packages:
   python3-doc (3.2.3-6)
   python3-tk (3.2.3-1)
   python3.2-doc (3.2.3-7+deb7u1)
   binfmt-support (2.0.12)
The following NEW packages will be installed:
   python3 (3.2.3-6)
   python3-minimal (3.2.3-6)
   python3.2 (3.2.3-7+deb7u1)
   python3.2-minimal (3.2.3-7+deb7u1)
0 upgraded, 4 newly installed, 0 to remove and 240 not upgraded.
Need to get 4246 kB of archives.
After this operation, 13.4 MB of additional disk space will be used.
Do you want to continue [Y/n]? Y
WARNING: The following packages cannot be authenticated!
  python3.2-minimal python3.2 python3-minimal python3
Install these packages without verification [y/N]? y
Err http://security.debian.org/ wheezy/updates/main python3.2-minimal armhf 3.2.3-7+deb7u1
  404  Not Found [IP: 151.101.0.204 80]
Err http://security.debian.org/ wheezy/updates/main python3.2 armhf 3.2.3-7+deb7u1
  404  Not Found [IP: 151.101.0.204 80]
Err http://ftp.us.debian.org/debian/ wheezy/main python3-minimal all 3.2.3-6
  404  Not Found [IP: 64.50.233.100 80]
Err http://ftp.us.debian.org/debian/ wheezy/main python3 all 3.2.3-6
  404  Not Found [IP: 64.50.233.100 80]
Failed to fetch http://security.debian.org/pool/updates/main/p/python3.2/python3.2-minimal_3.2.3-7+deb7u1_armhf.deb  404  Not Found [IP: 151.101.0.204 80]
Failed to fetch http://security.debian.org/pool/updates/main/p/python3.2/python3.2_3.2.3-7+deb7u1_armhf.deb  404  Not Found [IP: 151.101.0.204 80]
Failed to fetch http://ftp.us.debian.org/debian/pool/main/p/python3-defaults/python3-minimal_3.2.3-6_all.deb  404  Not Found [IP: 64.50.233.100 80]
Failed to fetch http://ftp.us.debian.org/debian/pool/main/p/python3-defaults/python3_3.2.3-6_all.deb  404  Not Found [IP: 64.50.233.100 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

尝试指定版本时，它也会失败：

root@beaglebone:~# sudo apt-get install python3=3.4
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Version '3.4' for 'python3' was not found

有什么建议吗？

谢谢！