Hello expert, when I install the Odoo14 community according to the link as following:

https://www.odoo.com/documentation/14.0/setup/install.html#linux

I meet the problem as below:

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:

odoo : PreDepends: init-system-helpers (>= 1.54~) but 1.51 is to be installed

Depends: python3-xlwt but it is not installable

Recommends: python3-ldap but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

How to solve this problem? 

Thank you very much in advance! Best regards!