Creating triggers

I would like to know if it is possible to use the logical AND operator in the creation of a trigger? From what I am seeing, I can only create a trigger using the OR operator. I would like to create something like:

(Field A = Y AND (Field B = Y OR Field C = Y))

which is logically different from what I am currently able to do:

(Field A = Y OR Field B = Y OR Field C = Y)

Please advise.

Thanks very much,