还是翻译apt-get的时候的不明白的句子

hyperslaver

upgrade
          upgrade is used to install the newest versions of all packages
          currently installed on the system from the sources enumerated in
          /etc/apt/sources.list. Packages currently installed with new
          versions available are retrieved and upgraded; under no
          circumstances are currently installed packages removed, or packages
          not already installed retrieved and installed. New versions of
          currently installed packages that cannot be upgraded without
          changing the install status of another package will be left at their
          current version. An update must be performed first so that apt-get
          knows that new versions of packages are available.

中间不太明白.请各位兄台帮忙

seasun

升级是用来安装所有软件包的最新版本，这些软件包是默认从sources.list列表中安装到系统中去的。可用的新版本的软件包被检索和升级；默认安装的软件包决不会被删除，没有安装的软件包也不会被检索和安装。如果没有改变原有软件包的安装状态，它将会留下系统中，软件包的新版本不会被升级。在执行apt-get upgrade前首先执行apt-get update升级下sources.list，这样使apt-get知道哪些软件的新版本是可用的。
Packages currently installed with new
versions available are retrieved and upgraded; under no
circumstances are currently installed packages removed, or packages
not already installed retrieved and installed. New versions of
currently installed packages that cannot be upgraded without
changing the install status of another package will be left at their
current version这一段我也没有理解其中的意思，大家再来翻译一下吧。

xjtuphy

Packages  currently  installed  with new versions available are retrieved and upgraded; under no  circumstances  are  currently  installed packages removed, or packages not already installed retrieved and installed. New  versions  of currently  installed  packages  that  cannot be upgraded without changing the install status of another package will be  left  at their current version. An update must be performed first so that apt-get knows that new versions of packages are available.


已安装的包如果有新版本发布，就下载并升级，但是绝不会删除，未安装的包则不会下载安装。如果升级已安装包到新版本会影响到其他包，则保持其版本不变。在此之前，需先行update以保证apt-get得到安装包的新版本信息。

seasun

New versions of currently installed packages that cannot be upgraded without changing the install status of another package will be left at their current version.
如果升级已安装包到新版本会影响到其他包，则保持其版本不变.这个翻译地比较好。

hyperslaver

Post by xjtuphy;1794898
Packages  currently  installed  with new versions available are retrieved and upgraded; under no  circumstances  are  currently  installed packages removed, or packages not already installed retrieved and installed. New  versions  of currently  installed  packages  that  cannot be upgraded without changing the install status of another package will be  left  at their current version. An update must be performed first so that apt-get knows that new versions of packages are available.


已安装的包如果有新版本发布，就下载并升级，但是绝不会删除，未安装的包则不会下载安装。如果升级已安装包到新版本会影响到其他包，则保持其版本不变。在此之前，需先行update以保证apt-get得到安装包的新版本信息。

你翻译的非常好,原来我弄不明白的是"under no  circumstances"这个词汇,应该是"绝不会"

Idiom: in no circumstances (under no circumstances)

      Never, not for any reason at all.
            Thesaurus: never, absolutely not, under no conditions, by no means, no way (slang).

Idiom: in the circumstances (under the circumstances)

      The situation being what it is or was.
            Thesaurus: for this reason, conditions being what they are, all things considered, as matters stand.

Idiom: reduced circumstances

      Poverty.

Etymology: 13c: from Latin circumstantia.

以上翻译来自
http://www.allwords.com/word-under%20no%20circumstances.html