active and passive.

I'm confused about active and passive voice. I understand what it is, but i still don't know when to apply it to a text. For example, is the phrase " But witnesses said they did not think the crash was the subject of the argument between the two men" active or passive? Katherine.

[Tdol]

It's active- in the passive, you could say 'witnesses said the crash was not thought to be the subject...'