Question

Which plural noun always takes a singular verb

Answer 1

Collective nouns

Hope this helps!! :)

Answer 2

Hi 

distances nouns , sums of money, periods of time ......only when considered as a unit :

50 years is the minimum sentence for that kind of crime 
2 miles is too far for me to walk
20 dollars is a normal price to pay for this .

But  
20 miles are separating those two cities
20 dollars have be found on the ground  next the coffee machine

collective nouns aren't always plural as money , people......

hope it helps