Question

In the sentence, "Not all research into regional English varieties requires such time, effort, and resources, however", why is it 'requires' and not 'require'?

Answer 1

I feel like it could go both ways, this kinda stumped me xD

Answer 2

Well, first off if you say the sentence aloud but replace 'requires' with 'require' it does sound odd and not fitting. Also, in the sentence, they are speaking about more than one research, if you get what I am saying. It was hard to phrase that x.x