Unfortunately, I have not found a proper way to type in Chinese characters!

When i want to install new software on my pear os8 it shows that "Requires installation of untrusted packages". It‘s really hard to figure out where the problem is before I searched it on the Internet.

Some pages told me that i need to change the sources, /etc/apt/sources.list, of my os. Finally if found this page:http://liuzhigong.blog.163.com/blog/static/17827237520121113103236820/ whose solution works. I replaced the username ‘maverick‘ to ‘trusty‘.Here is my sources.list:

deb http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu raring universe

"souces.list" of My Pear OS8