I am confused in be-verb tense.
He is/was my high school classmate. (Now I study in college).
Bill Clinton is/was the 42nd president of the United States.
This is/was my high school. (Now I study in college. When I pass through the place, I introduce it to my friend)
This is/was Apple's 2016 income. (In the presentation, I show my boss Apple's 2016 income).
According to my understanding, both of is and was are allowable.
Is it right?