Why is verb "to be" used in plural in the sentence below?
There were a quantity of overgrown lettuces.
The word quantity is a singular noun, isn't it?
From Practical English Usage, by Michael Swan:
"The expressions a number of and a group of are used with plural nouns and pronouns, and the verb that follows is also plural.
A number of my friends are on holiday.
A group of us have decided to hire a boat."
I assume that the expression a quantity of is used in the same way.
A quantity of lettuces were in the truck.
I see quantity as being different from all the others, since it can be used with non-count nouns.
A quantity of ethanol was....
A quantity of flour was....
A quantity of sand was....