grammar - Most of something is plural or singular?

I am writing a literature review. My question is which sentence is correct?

1. Most of the existing work focus on...


2. Most of the existing work focuses on ...


3. Most of the existing studies focus on ...

Thanks

Answer

If the object after "most" is singular then the verb is singular too, else if the object after "most" is plural then the verb is plural:

• Most of his ideas are silly. (ideas - plural, are - plural)


• Most of his money is spent on PC games. (money - singular (uncountable), is - singular)

Your second and third sentences are correct. The first one is incorrect.