You should never use singular noun after "of the" right?

[Aikuzo3]

One book says:
"Plural Nouns Follow "of the" Expressions"
"Use a plural noun after expressions such as one of the, all of the, each of the, and so on."

Eg. One "of the" anthropoligists in the twentieth century was Louis Leakey.

So, when I read this, I assume on all "off the" sentences... I must "only" use plural nouns... and it made sense because the noun after "of the" has to be atleast two or more. (Not one/singular noun)

But, I'm reading another book(Blue Book of Grammar) where it says things like:

"All of the pie is gone"
"Some of the pie is gone"

I don't get why they use "All of the" when the "pie" is only singular. It made sense to me if it says "All 'pieces' of the pie are gone." Same with "some" - pie is singular so it's not making sense to me. I heard "some" can only be used in plural nouns. It's like saying "Some of the guy/person is walking."

Could anyone explain these to me, thanks.

 

[probus]

"one of the, all of the, each of the, and so on."

You have generalized far too much from the phrase "and so on." It includes only phrases that are grammatically similar to the phrases that precede it, for example many of the, much of the, few of the, etc."

I'll give you one example of a singular noun following "of the", and your homework is to construct ten more of your own: The dangers of the night are fearsome to many."

 

[emsr2d2]

All of the pie is gone = The pie is gone = The entire amount of pie is gone

 

[Tdol]

One book says:
"Plural Nouns Follow "of the" Expressions"
"Use a plural noun after expressions such as one of the, all of the, each of the, and so on."

Which book was this?

all/a lot/lots, etc can be used with uncountable and countable nouns.

I spent all of the money. (uncountable)
I met all of the people. (countable)