I need to know. I really need to know.

I need to know why someone who knows how to check email would read an email and open an attachment from someone they don't know, even someone they do know. Please explain that to me.

If one in twenty parcels you get from the U.S. Postal Service was a mail bomb would you just open any mail willy nilly like?

If one was..Is that right?

One was..one were
I was..I were
He was..he were
you was..you were
It was..it were

Where the hell did I learn my basic verb conjugation?