how to make a sub list from a long list using the component name?

Hello, R users,
I have a long list with over 20,000 elements (say foo), now I want to make a sub
list of 30 elements from this list using the component names such as subname<-c(
"a", "b", "d", "f", "g", "h", "o", "q",...). One way to do it is to make rest of
elements in the list NULL, that is too silly. Is there another way to make the
sub list?
Thanks
Joshua