(Located on) the firefly’s lower abdomen (is) a mass of luminescent cells in which oxygen (combines) with a substance called luciferin (to produce) the insect’s distinctive glow.
why the the answer isn’t B i saw a similar question which describes a similer pattern but the answer is are.
a number of workers ARE beginning to protest the economic politics.
why in the first question the answer is IS and not ARE? “a number of” “A mass of”
A number of is plural, while the number of is singular. This is a rule. Just follow it. In this example, it is telling you a mass so it is one thing so singular.
So there is no error right?
As far as I know, yes
The way I think of it is:
How many masses are there? We know that. One. There is one SINGULAR mass.
How many people are there? A number. We don’t know what that number is. It could be one singular person, or it could be a hundred (plural) people.
In the end, though, it might just be one of those things you have to memorize.
i think i got it, thank u!