发布文件中的“日期”条目无效

Question

我有 Ubuntu 16.04。当我做

sudo apt update

我得到以下输出：

W: Invalid 'Date' entry in Release file /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_xenial-security_InRelease
W: Invalid 'Date' entry in Release file /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_xenial-backports_InRelease
W: Invalid 'Date' entry in Release file /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_xenial-proposed_InRelease

我该如何解决这个问题？

当我做 ls/var/lib/apt/lists我得到输出：

http://paste.ubuntu.com/17059541/

当我这样做时，gedit /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_xenial-security_InRelease我得到输出：

http://paste.ubuntu.com/17059579/

当我这样做时，gedit /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_xenial-backports_InRelease我得到输出：

http://paste.ubuntu.com/17059594/

当我这样做时，gedit /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_xenial-proposed_InRelease我得到输出：

http://paste.ubuntu.com/17059610/

如何更正这个无效的“日期”条目？