Breakdown of El asesino acababa de forzar la ventana.
la ventana
the window
acabar de
to have just
el asesino
the murderer
forzar
to force
Questions & Answers about El asesino acababa de forzar la ventana.
Since this lesson is about past conjecture, how would we change this sentence to mean 'The murderer must have just forced the window'?
This sentence states a fact. To turn it into an assumption about the past, you would use the conditional perfect of acabar: El asesino habría acabado de forzar la ventana (The murderer must have just forced the window).
Why is acabar de used here instead of a perfect tense?
The phrase acabar de + infinitive is a special formula that means 'to have just done something'. To talk about the past ('had just done'), you put acabar in the imperfect tense. So, acababa de forzar translates perfectly to 'had just forced'.
Why do we use the imperfect tense (acababa) instead of the preterite (acabó)?
Could I use the past perfect (había forzado) to express this?
You could say había forzado to mean 'had forced', but it completely drops the word 'just'. Acababa de forzar specifically emphasizes that the break-in happened immediately before whatever happened next in the story.