我尝试了mongodb官方网站提供的在ubuntu 14.04服务器上安装mongodb的步骤，但出现以下错误
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
linux-image-extra-4.4.0-138-generic : Depends: linux-image-4.4.0-138-generic but it is not going to be installed
linux-image-generic-lts-xenial : Depends: linux-image-4.4.0-138-generic but it is not going to be installed
mongodb-org : Depends: mongodb-org-shell but it is not going to be installed
Depends: mongodb-org-server but it is not going to be installed
Depends: mongodb-org-mongos but it is not going to be installed
Depends: mongodb-org-tools but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).
那我现在该怎么办。