As per the subject-verb agreement, if a subject is singular, its verb must also be singular
He sings.
if a subject is plural, its verb must also be plural.
They sing.
I have seen some examples of "cut" on the internet that created some confusion.
- Tom has cut his finger.
- Tom often cuts classes.
(Tom is singular - so cuts are used)
- Tom cut classes again.
(why is cut used here and not cuts. Tom is singular)
My mother cut the cake.
(My mother is singular, then shouldn't we use cuts here)
This knife cuts well.
(knife is also singular)
Each cone cuts out an area on the surface equally inclined to the cone axis.