George is going to talk about the geography of his country, but I'd rather he __________ more on its culture.
Which do you enjoy ____ your weekend, swimming or fishing?
I think this is the very work that we must finish ____ her.
The work he devoted his time to _____ worth praising.
The theory he sticks to ______ to be of no use in our studies.
The man you referred to _____ just now.