Plural or singular verb in this sentence...?

[Mehrgan]

Hi there,

I've just come across this sentence and was wondering why the verb is in plural. Is it 'decades' or the 'concept of scientific research' which determines the verb?


"Luckily, decades of scientific research have helped us figure out how to brew, and drink, that perfect cup of joy."

 

[Raymott]

Decades have.
"A decade of scientific research has ..."

 

[Mehrgan]

Sorry if I'm questioning something off-topic, but can we say, 'what we need are/is decades of research...'?

 

[Raymott]

I'd go with 'is' there, with the justification that it's one period of research lasting a few decades.