我找不到此问题的解决方案：
constantia@constantia:~$ sudo apt-get install build-essential
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
build-essential : Depends: dpkg-dev (>= 1.13.5) but it is …我尝试为 abacron 执行此任务：
dm@dm-system:~$ cat /etc/anacrontab
# /etc/anacrontab: configuration file for anacron
# See anacron(8) and anacrontab(5) for details.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
HOME=/root
LOGNAME=root
# These replace cron's entries
1 5 cron.daily run-parts --report /etc/cron.daily
7 10 cron.weekly run-parts --report /etc/cron.weekly
@monthly 15 cron.monthly run-parts --report /etc/cron.monthly
@daily 5 /home/dm/Devel/btsync && notify-send "Btsync loaded (pid `pidof btsync`)" "Link <a href='http://0.0.0.0:8888/gui/'>here</a>."
这个命令在我的 xubuntu 终端上做得很好
/home/dm/Devel/btsync && notify-send "Btsync loaded (pid `pidof btsync`)" "Link <a href='http://0.0.0.0:8888/gui/'>here</a>."
但是当我启动我的笔记本时，我在 /var/syslog 中看到：
Aug 14 10:49:06 dm-system …我无法安装 lxml。在系统中，我有 python-lxml 包，但我需要其他包...请帮忙，如果可以的话 - 我的任务是安装 lxml 以使用 virtualenv 在虚拟环境中进行开发。我发现此解决方案已成功修复安装 lxml：
$ sudo apt-get install libxml2 libxml2-dev libxslt-dev build-essential python-dev
$ sudo ldconfig
然后：
$ source bin/activate # for activate enviroment
(env) $ pip install lxml
但是我有很多问题。
第一个问题是使用依赖项安装 build-essential -为什么 build-essential 失败？
解决了！谢谢！
接下来我有这个（输出）：
(env) $ pip install lxml
...
i686-linux-gnu-gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security build/temp.linux-i686-2.7/src/lxml/lxml.etree.o -lxslt -lexslt -lxml2 -lz -lm -o build/lib.linux-i686-2.7/lxml/etree.so
/usr/bin/ld: …