These expressions have similar meanings to the determiners much, many and most, but the grammar is not quite the same. Of is used after these expressions even before nouns with no determiner.
- Plenty of shops open on Sunday mornings. (NOT Plenty shops —)
- Many shops open on Sunday mornings. (NOT Many of shops —)
- There is not a lot of rice left. (NOT There is not a lot rice left.)
- There is not much rice left. (NOT There is not much of rice left.)
A lot of and lots of
These are rather informal. There is not much difference between a lot of and lots of. They are both used mainly before singular uncountable and plural nouns, and before pronouns. When a lot of/lots of is used before a plural subject, the verb is plural.
- A lot of my friends live abroad.
- Lots of time is needed to learn a language.
Plenty of means enough and more. It is used before singular uncountable and plural nouns.
- There is plenty of time.
- Plenty of shops accept credit cards.
A large amount of, a great deal of and a large number of
These expressions are rather formal. A large amount of and a great deal of are generally used before uncountable nouns.
- She has spent a great deal of time in Europe.
A large number of is used before plural nouns. The following verb is plural.
- A large number of issues still need to be addressed.