Question

colocar esta frase no presente continuo
they (talk) about the invoices

Answer 1

they are talking about the invoices

espero ter ajudado

Answer 2

Para colocar a frase no present continuous, você precisa olhar o sujeito 
 I
You
He
She
It
We
They


Depois, dependendo do sujeito, entra o verbo to be

I am 
You are
He is
She is
It is
We are
They are

E agora o verbo conjugado

Ou seja, " sujeito + verbo to be + verbo com -ING + complemento"

Na frase "they (talk) about the invoices"

They - sujeito
Are - verbo to be
Talking - verbo conjugado com ING
About the invoices - complemento

They are talking about the invoices.

Espero que dê para entender.