Some singular subjects are easy to recognize. For example, a singular count noun takes a singular simple present verb:
|A car needs gas.||A passport is required to enter the U.S.|
A non-count noun is also singular and takes a singular simple present verb:
|Money is important.||Food gives us energy.|
Here are some stranger things that also take a singular verb:
I: each & every
Each student speaks in class.
Every person is here.
Everyone knows the answer.
Everybody uses a cell phone.
Everything is finished.
II: most group nouns
My family doesn’t live with me.
The class is ready for the quiz.
The army demands hard work.
(Exception: The police patrol here regularly. “Police” takes a plural verb.)
III: Gerund subjects
Learning English takes effort.
In fact, gerund subjects take a singular verb even when the object of the gerund is plural!
Having many friends is fun.
Reading books makes you smarter.
Sometimes a singular subject is separated by another phrase or clause which can make you forget that the subject is singular.
A way to make a lot of friends is to invite people to do things with you.
The problem with living far away from your family and friends is loneliness.
Therefore, next time you edit a paper, make sure you find all of your singular subjects.