Various methods can be used to reduce or increase the amount of friction between surfaces in contact.
(Various methods; can be used; to reduce or increase the amount of friction between surfaces in contact) (Various methods; to reduce; ) (Various methods; to increase; the amount of friction between surfaces in contact)
Various methods Various methods Various methods
can be used to reduce to increase
to reduce or increase the amount of friction between surfaces in contact
the amount of friction between surfaces in contact