I have written
Me pregunto si lo que he escrito era correcto.
I wonder if what I wrote was correct.
I wrote this book.
He escrito todos los números hasta el treinta y uno.
I have written all the numbers up to thirty-one.
I have written you three letters.
Yo, un anciano, le he escrito a un anciano sobre la vejez.
I, an old man, have written to an old man about old age.
I have written him a letter.
Lo que he escrito en ese papel es una garantía, no una promesa.
What I have written on that paper is a guarantee, not a promise.
— El cartero (y Pablo Neruda) (1994)