Present passive: Affirmative and negative.

The passive explains how things happpen. Sometimes we don´t know, or we don´t say, who does the action. Use by before the person or thing that does the action.

Affirmative

            be 
The magazine is sent to the stores.

The articles are written by the reporters.

Negative

Be(+not)

The magazines isn´t made here

The articles aren´t written by me.

Aquí un video para que puedan ver más sobre este tema.

https://www.youtube.com/watch?v=2szHTc5S0fc