3.- Voz pasiva: he wites a book = a book is written
he is Writing a book = a book is being written
he wrote a Book = a book was written
he was Writing a book = a book was being written
he has Written a book = a book has been written
he had Written a book = a book had been written
he will Write a book = a book will be written
Second conditional: if + past simple en la condicion + would con el verbo en la forma base en el resultado.
tercer condicional: if + past perfect simple + would have + participio en el resultado.