Apache2::Request and other modules

[ypeng]

Hello

In my modperl handler, I only use Apache2::Request module.
What relations are there between Apache2::Request and the following 
modules?

use Apache2::RequestRec ();
use Apache2::RequestIO ();
use Apache2::Connection ();
use APR::Table ();


Should I include them in startup.pl as well as Apache2::Request?

Thanks.