我正在尝试在我的 Ubuntu 15.10 上安装 python-graph-tools，但是它说
python-graph-tool : Depends: libboost-iostreams1.55.0 but it is not installable
Depends: libboost-python1.55.0 but it is not installable
Depends: libboost-regex1.55.0 but it is not installable
Depends: libcairomm-1.0-1 (>= 1.6.4) but it is not installable
Depends: python-scipy but it is not going to be installed
Depends: libboost-graph1.55.0 but it is not installable
Depends: libboost-system1.55.0 but it is not installable
Depends: libboost-thread1.55.0 but it is not installable
Depends: python-matplotlib but it is not going to be installed
Depends: libcgal10 but it is not installable
E: Unable to correct problems, you have held broken packages.
虽然我的电脑上有 libboost-iostream 1.58。我还尝试使用以下方法删除此包：
sudo sudo apt-get --purge remove libboost-iostreams
并尝试使用代码安装 libboost iostream 1.55
sudo apt-get install libboost-iostreams-dev 1.55
但它再次安装了 1.58 版本。